在三角形ABC中,AB=AC,D为AC上一点,且DA=DB,BD=BC求三角形ABC各内角度数 图形是个等腰三角形

因：AB=AC 所以：角C=角ABC 角A=180度-2角C ································⑴
因：DA=DB 所以：角A=角ABD 角ADB=180-2角A·································⑵
因：BD=BC 所以：角C=角BDC 角DBC=180度-2角C······························⑶
由：⑴、⑶ 得：角A=角DBC
又因：角A=角ABD
所以：角ABC=2角A 角C=2角A
代入⑴得：角A=180度-4角A
角A=36度
角C=角ABC=36度*2=72度