解:①△ABC和△DEF相似.理由如下:∵根据图示知:AB=2 5 ,AC= 5 ,BC=5,ED=4 2 ,DF=2 2 ,EF=2 10 ,∴ AC DF = AB ED = BC EF = 10 4 ,∴△ABC∽△DEF;②△ACB∽△DP3P2.理由如下:∵由①知,△ABC∽△DEF,∴∠D=∠A.连接DP2P3,DP3= 2 ,DP2=