如图,四边形ABCD是菱形,AF⊥BC交BD于E,交BC于F.求证:AD^2=1/2DE×DB.
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![如图,四边形ABCD是菱形,AF⊥BC交BD于E,交BC于F.求证:AD^2=1/2DE×DB.](/uploads/image/z/856835-35-5.jpg?t=%E5%A6%82%E5%9B%BE%2C%E5%9B%9B%E8%BE%B9%E5%BD%A2ABCD%E6%98%AF%E8%8F%B1%E5%BD%A2%2CAF%E2%8A%A5BC%E4%BA%A4BD%E4%BA%8EE%2C%E4%BA%A4BC%E4%BA%8EF.%E6%B1%82%E8%AF%81%EF%BC%9AAD%5E2%3D1%2F2DE%C3%97DB.)
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如图,四边形ABCD是菱形,AF⊥BC交BD于E,交BC于F.求证:AD^2=1/2DE×DB.
如图,四边形ABCD是菱形,AF⊥BC交BD于E,交BC于F.求证:AD^2=1/2DE×DB.
如图,四边形ABCD是菱形,AF⊥BC交BD于E,交BC于F.求证:AD^2=1/2DE×DB.
取DE中点H,连AH,因∠EAD=90°,则DH=AH
∴∠HAD=∠ADH
∵四边形ABCD是菱形
∴∠ABD=∠CBD
∵∠ADH=∠CBD
∴∠DAH=∠ABD
∵∠ADB=∠HDA
∴△AHD∽△BAD
∴AD:DH=DB:AD
∴AD^2=DH*DB
∵DH=1/2DE
∴AD^2=1/2DE×DB.