
连AM,AB=AC,m为bc中点,所以AM垂直BC,bd垂直l于d,ce垂直l于e,有A.M.B.D四点共圆,A.M.C.E四点共圆由A.M.B.D四点共圆得角ADM=角ABM,A.M.C.E四点共圆得角AEM=角ACM,由AB=AC得角ABM=角ACM,所以角ADM=角AEMMD=ME

连AM,AB=AC,m为bc中点,所以AM垂直BC,bd垂直l于d,ce垂直l于e,有A.M.B.D四点共圆,A.M.C.E四点共圆由A.M.B.D四点共圆得角ADM=角ABM,A.M.C.E四点共圆得角AEM=角ACM,由AB=AC得角ABM=角ACM,所以角ADM=角AEMMD=ME