证明:连接BC在Rt△ABC和Rt△DCB中BC=CBAC=BD∴Rt△ABC≌Rt△DCB (HL)∴AB=DC在△AOB和△纤吵毕DOC中∠A=∠D∠AOB=∠DOCAB=DC∴△AOB≌碰汪△DOC (AAS)∴毁芹OB=OC