证明:在梯形ABCD中,∵AD‖BC,AC与BD相交于O点,∴∠AOD=∠BOC,∠ADB=∠DBC,即△AOD∽△BOC,OA/OC=OD/OB在△BOE与△COD中,∵BE‖CD,BD与CE相交于O点,∴∠BOE=∠COD,∠BEC=∠DCE即△BOE∽△COD,OC/OE=OD/OB即OA/OC=OD/O...