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<span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">问题提出</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">1</span></span><span style="line-height:150%"><span style="font-family:新宋体">）如图</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">①</span></span><span style="line-height:150%"><span style="font-family:新宋体">，已知直线</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">l</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">及</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">l</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">外一点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">A</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，试在直线</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">l</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">上确定</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">B</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">、</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">C</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">两点，使∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BAC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">90</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，并画出这个</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">Rt</span></span><span style="line-height:150%"><span style="font-family:新宋体">△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">问题探究</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span><span style="line-height:150%"><span style="font-family:新宋体">）如图</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">②</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">O</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">是边长为</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">28</span></span><span style="line-height:150%"><span style="font-family:新宋体">的正方形</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">的对称中心，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">M</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">是</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">边上的中点，连接</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OM</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">．试在正方形</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">的边上确定点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，使线段</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ON</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">和</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OM</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">将正方形</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">分割成面积之比为</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">1</span></span><span style="line-height:150%"><span style="font-family:新宋体">：</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">6</span></span><span style="line-height:150%"><span style="font-family:新宋体">的两部分．求点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">到点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">M</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">的距离．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">问题解决</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">3</span></span><span style="line-height:150%"><span style="font-family:新宋体">）如图</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">③</span></span><span style="line-height:150%"><span style="font-family:新宋体">，有一个矩形花园</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AB</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">30<i>m</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">40<i>m</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">．根据设计要求，点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">E</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">、</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">F</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">在对角线</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">上，且∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EAF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">60</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，并在四边形区域</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AECF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">内种植一种红色花卉，在矩形内其他区域均种植一种黄色花卉．已知种植这种红色花卉每平方米需</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">210</span></span><span style="line-height:150%"><span style="font-family:新宋体">元，种植这种黄色花卉每平方米需</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">180</span></span><span style="line-height:150%"><span style="font-family:新宋体">元．试求按设计要求，完成这两种花卉的种植至少需费用多少元？（结果保留整数．参考数据：</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/9e1fc3d74a520db12e494aab42dd7f73.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">≈</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">1.4</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/6ac745c38c13ba41cb7e6896e5c99563.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">≈</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">1.7</span></span><span style="line-height:150%"><span style="font-family:新宋体">）</span></span></span></span></span><br /> <img height="130" src="/uploads/meth/20210114/3f2b8b5cb10aff01f1bd284867530252.png" width="447" />
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<span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">解：（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">1</span></span><span style="line-height:150%"><span style="font-family:新宋体">）如图</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">①</span></span><span style="line-height:150%"><span style="font-family:新宋体">所示，</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">Rt</span></span><span style="line-height:150%"><span style="font-family:新宋体">△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">即为所求．（只要画出一个符合要求的</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">Rt</span></span><span style="line-height:150%"><span style="font-family:新宋体">△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">即可）；</span></span></span></span></span><br /> <img height="106" src="/uploads/meth/20210114/2b6791bcd8f03e1afd4eb30f273fd93c.png" width="136" /><br /> <br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span><span style="line-height:150%"><span style="font-family:新宋体">）如图</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">②</span></span><span style="line-height:150%"><span style="font-family:新宋体">，∵</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">O</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">是正方形</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">的对称中心，且</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BM</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">CM</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">△</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BOM</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/f41c55f862b7316f20b184e46cce680f.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">28</span></span><sup><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span></span></sup><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/dd1a6b022f5a04f3166bb88f2a47c140.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">28</span></span><sup><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span></span></sup><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">不可能在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BM</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">上，由对称性，可知点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">也不可能在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">MC</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">上，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">显然，点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">不在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">边上，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴设点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AB</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">边上，连接</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ON</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">由题意，得</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/534828cf32bcf44f2acf07cab529daf3.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BN</span></span></i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">+14</span></span><span style="line-height:150%"><span style="font-family:新宋体">）×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">14</span></span><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/7dbdf9a7dffaf6853b21322d76f7935e.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">28</span></span><sup><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span></span></sup><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">解之，得</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BN</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span><span style="line-height:150%"><span style="font-family:新宋体">．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">由对称性知，当点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">N</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">CD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">边上时，可得</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">CN</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span><span style="line-height:150%"><span style="font-family:新宋体">．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">MN</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="24" src="/uploads/meth/20210114/256b64ac1baa21fd37712d4ad084cc21.png" width="67" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">10</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/2ccc0ea17ecc85b59c8dcdb85af367d2.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">．</span></span></span></span></span><br /> <br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">3</span></span><span style="line-height:150%"><span style="font-family:新宋体">）如图</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">③</span></span><span style="line-height:150%"><span style="font-family:新宋体">所示，过点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">A</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">作</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">⊥</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">于点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">H</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <img height="139" src="/uploads/meth/20210114/8b80d9a514a08f11c43fa6be3085093c.png" width="111" /><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">在</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">Rt</span></span><span style="line-height:150%"><span style="font-family:新宋体">△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">中，∵∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BAD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">90</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AB</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">30</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">40</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="24" src="/uploads/meth/20210114/d5f805c1f97c54bf58690ad9ecdd84ba.png" width="75" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="24" src="/uploads/meth/20210114/2d8c9f8a46700b236ca1b729ccc758f5.png" width="75" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">50</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∵</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/3e0ef1b879e0832deb1a96b2b9ca838c.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">•</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AB</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">•</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/d1348dd0f9042adb07220f2b3bec1764.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">•</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">•</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">24</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∵四边形</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">是矩形，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">△</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AEF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">△</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">CEF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">四边形</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AECF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2<i>S</i></span></span><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">△</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AEF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span><span style="line-height:150%"><span style="font-family:新宋体">×</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/e7e6841330b2e1e6dfcf29c95f94598b.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">•</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">24<i>EF</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">由题意可知，只有</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">四边形</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AECF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">最小时，按设计要求在矩形</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABCD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">内种植红、黄两种花卉的费用最低．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">要使</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">四边形</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AECF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">最小，就需</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">最短，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∵</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">⊥</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">tan</span></span><span style="line-height:150%"><span style="font-family:新宋体">∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">HAD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">tan</span></span><span style="line-height:150%"><span style="font-family:新宋体">∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ABD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/803e3e620eb994825ec993378605abf2.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/05cada76648322c828d55dfc2274017c.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">tan</span></span><span style="line-height:150%"><span style="font-family:新宋体">∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BAH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">tan</span></span><span style="line-height:150%"><span style="font-family:新宋体">∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">ADB</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="35" src="/uploads/meth/20210114/1d9a3a700acc1feca2a662958c4d0ae3.png" width="13" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/19a600844c56f0a8872062dae118da55.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">HAD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">60</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BAH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">60</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">又∵∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EAF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">60</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">E</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">、</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">F</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">两点分布在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">异侧．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AEF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">为锐角三角形，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">作其中任一锐角△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AEF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">的外接圆</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Cambria Math","serif"">⊙</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">O</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，过</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">O</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">作</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OG</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">⊥</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">于点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">G</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，连接</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OA</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">、</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，则</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2<i>GF</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">，∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">GOF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝∠</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EAF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">60</span></span><span style="line-height:150%"><span style="font-family:新宋体">°，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">在</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">Rt</span></span><span style="line-height:150%"><span style="font-family:新宋体">△</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OGF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">中，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2<i>OG</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">GF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/9e3f1e223b91f9cc2bf185adb7b183ef.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OG</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/93ea5feb4e7141a28c91a7ffea5204c8.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OG</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">又∵</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OA</span></span></i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">+<i>OG</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">≥</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OA</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2<i>OG</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2<i>OG</i>+<i>OG</i></span></span><span style="line-height:150%"><span style="font-family:新宋体">≥</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">24</span></span><span style="line-height:150%"><span style="font-family:新宋体">，得</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OG</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">≥</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">8</span></span><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">2</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/72d2d8982db9bf9f096f3a610173b50d.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">OG</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">≥</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">16</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/1371c0c59daa8a1fefab9fcf7afab0e3.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴当圆心</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">O</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">上，即</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AE</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">时，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">16</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/c34159e86e612a7f04f80bd6dbf69ded.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">EH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">8</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/53ab3d2c48eca68531fe4c10fa35a547.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">18</span></span><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">FH</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">8</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/7e9a0f8107927c7f801c91288ccf56bc.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＜</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">32</span></span><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">HD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴当</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AE</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AF</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">时，点</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">E</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">、</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">F</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">在</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">BD</span></span></i><span style="line-height:150%"><span style="font-family:新宋体">上，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><i><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">S</span></span></i><sub><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:新宋体">四边形</span></span></span></sub><i><sub><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif"">AECF</span></span></span></sub></i><span style="line-height:150%"><span style="font-family:新宋体">的最小值为</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">24</span></span><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">16</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/072c1f45338039b252e95ce9d2d5df0a.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">384</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/b2c504996a971f6740bd93e2b9b1fcc0.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">，</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">384</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/4211073316abb09cd28dff2485caa278.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">210+</span></span><span style="line-height:150%"><span style="font-family:新宋体">（</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">30</span></span><span style="line-height:150%"><span style="font-family:新宋体">×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">40</span></span><span style="line-height:150%"><span style="font-family:新宋体">﹣</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">384</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/69777c1515ae398b41edafca585aa3b8.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">）×</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">180</span></span><span style="line-height:150%"><span style="font-family:新宋体">＝</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">216000+11520</span></span></span></span></span><img height="18" src="/uploads/meth/20210114/8b616a3741a4aea241d0ec2e4046ad66.png" width="20" /><span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">≈</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">235584</span></span><span style="line-height:150%"><span style="font-family:新宋体">（元）．</span></span></span></span></span><br /> <span style="font-size:10.5pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="line-height:150%"><span style="font-family:新宋体">∴按设计要求，完成这两种花卉的种植至少需费用约为</span></span><span lang="EN-US" style="line-height:150%"><span style="font-family:"Times New Roman","serif"">235584</span></span><span style="line-height:150%"><span style="font-family:新宋体">元．</span></span></span></span></span>
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