『‼』数学几何题目..A/\/ \D/ \/ \Bˉˉˉˉ C如图,已知△ABC中,AB=AC,∠A=36°,∠ACB的平分线交AB于D,BD=2,求AC的长.(注:CD不太好画 请自己画一下)THANK!````A/\D / \/ \/ \ˉˉˉˉˉB C
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![『‼』数学几何题目..A/\/ \D/ \/ \Bˉˉˉˉ C如图,已知△ABC中,AB=AC,∠A=36°,∠ACB的平分线交AB于D,BD=2,求AC的长.(注:CD不太好画 请自己画一下)THANK!````A/\D / \/ \/ \ˉˉˉˉˉB C](/uploads/image/z/8791932-12-2.jpg?t=%E3%80%8E%26%238252%3B%E3%80%8F%E6%95%B0%E5%AD%A6%E5%87%A0%E4%BD%95%E9%A2%98%E7%9B%AE..A%2F%5C%2F+%5CD%2F+%5C%2F+%5CB%CB%89%CB%89%CB%89%CB%89+C%E5%A6%82%E5%9B%BE%2C%E5%B7%B2%E7%9F%A5%E2%96%B3ABC%E4%B8%AD%2CAB%3DAC%2C%E2%88%A0A%3D36%C2%B0%2C%E2%88%A0ACB%E7%9A%84%E5%B9%B3%E5%88%86%E7%BA%BF%E4%BA%A4AB%E4%BA%8ED%2CBD%3D2%2C%E6%B1%82AC%E7%9A%84%E9%95%BF.%28%E6%B3%A8%3ACD%E4%B8%8D%E5%A4%AA%E5%A5%BD%E7%94%BB+%E8%AF%B7%E8%87%AA%E5%B7%B1%E7%94%BB%E4%B8%80%E4%B8%8B%29THANK%21%60%60%60%60A%2F%5CD+%2F+%5C%2F+%5C%2F+%5C%CB%89%CB%89%CB%89%CB%89%CB%89B+C)
『‼』数学几何题目..A/\/ \D/ \/ \Bˉˉˉˉ C如图,已知△ABC中,AB=AC,∠A=36°,∠ACB的平分线交AB于D,BD=2,求AC的长.(注:CD不太好画 请自己画一下)THANK!````A/\D / \/ \/ \ˉˉˉˉˉB C
『‼』数学几何题目..
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如图,已知△ABC中,AB=AC,∠A=36°,∠ACB的平分线交AB于D,BD=2,求AC的长.
(注:CD不太好画 请自己画一下)
THANK!````
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B C
『‼』数学几何题目..A/\/ \D/ \/ \Bˉˉˉˉ C如图,已知△ABC中,AB=AC,∠A=36°,∠ACB的平分线交AB于D,BD=2,求AC的长.(注:CD不太好画 请自己画一下)THANK!````A/\D / \/ \/ \ˉˉˉˉˉB C
∵AB=AC,∠A=36°,∴∠ACB=∠B=(180°-36°)/2=72°,
∵AD平分∠ACB,∴∠ACD=∠BCD=72°/2=36°.
∠CDB=180°-∠B-∠BCD=72°.
∴AD=CD=CB,△ABC∽△CDB,AC/CB=CB/BD,
设AC=x,x/(x-2)=(x-2)/2,
解得x=3+√5.