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8 lines
567 B
8 lines
567 B
2 years ago
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- 直角三角形，斜边中线，等于斜边一半 $BG=\frac{1}{2}EF=2$
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- $BG$长度固定，则$G$在以$B$为圆心,长度为$2$的圆上运动
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- 四边形面积最小，可以看成上面的三角形$ACD$是固定值，只要$\triangle AGC$面积最小即可，从$G$向$AC$引垂线，则$S_{\triangle AGC}=\frac{1}{2}AC\times GM$
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- $GM$什么时候最短呢？
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- $GM>=BM-BG>=BH-BG$
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所以求出$BH$即可，按面积相等求解吧
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