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问题: 三角形

解答:

1)就知道是相似的矩形


2)做BC边的高AH,GD =EF =x,CD=2x
根据AHB ,GDB相似三角形
AH/GD =BH/BD
===>y/x =BH/BD
===>y/(y-x)=BH/(BH-BD) =BH/DH .........(1)
同理=====>y/(y-x)=CH/HE.......(2)
(1),(2) ===>y/(y-x)=CH/HE =BH/DH
和比定理 ===>y/(y-x)=(CH+BH)/(DH+HE) =BC/DE =5/2x
====>2xy=5(y-x)
===>y=5x/(5-2x)


3)可以,找到DE中点O,连接OG,OF
OG=OF=(√2)x EF=2X ====>OEF等腰直角