题目

如图2-1-3, =,在上任取一点P,PB、PC与AD的交点分别为E、F,则图中相似三角形的组数是(    )图2-1-3A.2                B.3                   C.4              D.6 答案：解:∵,∴∠B=∠PDE.又∠AEB=∠PED,∴△ABE∽△PED.同理,△APF∽△CDF.∵=,∴∠APB=∠CPD.∵,∴∠PAD=∠PCD.∴△APE∽△CPD.同理,△ABP∽△FDP.答案:C

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