OA=OC,OD=OB,角AOB=角COD,所以△AOB≌△COD 则AB=CD同理：OA=OC,OE=OF,角AOE=角COF,所以△AOE≌△COF 则AE=CFOB=OD,OE=OF,角BOE=角DOF,所以△BOE≌△DOF 则BE=DF因为 AB=CD AE=CF BE=DF所以 △ABE≌△CDF...