如图,A,B,C三点在⊙O上,且AB=AC,弦AE交BC于D,求证:AB²=AD·AE.
问题描述:
如图,A,B,C三点在⊙O上,且AB=AC,弦AE交BC于D,求证:AB²=AD·AE.
答
∵AB=AC∴∠ACB=∠ABC=∠AEB
又∠BAE公共.所以△ABD和△AEB相似
即AB/AD=AE/AB
即AB²=AD·AE