初二上学期数学有关全三角形的问题

证明：∵AC⊥BC，DB⊥BC∴∠ACB=∠DBC=90°在Rt△ABC和Rt△DCB中AB=DCCB=BC∴△ABC≌△DCB∴∠ABC=∠DCB∴∠ACB-∠DBC=∠DCB-∠ABC即∠ABD= ∠ACD∴∠ACD=∠ABD

证明：∵AC⊥BC，DB⊥BC∴∠ACB=∠DBC=90°∵AB=DC，CB=BC∴△ABC≌△DCB∴∠ABC=∠DCB∴90°-∠DCB=90°-∠ABC∴∠ACD=∠ABD