证明:在Rt△ABC和Rt△DCB中 BD=AC CB=BC ,∴Rt△ABC≌Rt△DCB(HL),∴∠OBC=∠OCB,∴BO=CO.
证明:∴OB=OC理由:∵∠A=∠D=90°∴△ABC与△BCD是Rt△在Rt△ABC与Rt△BCD中{BC=BC{AC=BD∴Rt△ABC≌Rt△BCD(HL)∴AB=CD在△AOB与△COD中{∠A=∠D{∠AOB=∠COD{AB=CD∴△AOB≌△COD(AAS)∴OB=OC