
一道几何解答题
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2013-09-24 · 知道合伙人教育行家
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作△DEF的高DH,则DH=√2/2
△DCH∽△ADH∽△ACD
AD^2+DC^2=AC^2
DH^2/AD^2+DH^2/DC^2=DC^2/AC^2+AD^2/AC^2=1
1/DH^2=1/AD^2+1/DC^2
1/DC^2=1/DH^2-1/AD^2=2-1/4=7/4
BC=4√7/7
请采纳
△DCH∽△ADH∽△ACD
AD^2+DC^2=AC^2
DH^2/AD^2+DH^2/DC^2=DC^2/AC^2+AD^2/AC^2=1
1/DH^2=1/AD^2+1/DC^2
1/DC^2=1/DH^2-1/AD^2=2-1/4=7/4
BC=4√7/7
请采纳
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