过E作EF//AD,交BC于F,因为AE=EC,所以DF=FC,则
EF=AD/2=9,设AD、BE交点为M,
因为,AB=AC,AD⊥BC,得BD=DC,DF:BF=2:3,可求得,MD=6,ME=5,过M作BC的平行线.交EF于H,得EH=9-6=3.MH=4,推出,AB=4MH=16
过E作EF//AD,交BC于F,因为AE=EC,所以DF=FC,则
EF=AD/2=9,设AD、BE交点为M,
因为,AB=AC,AD⊥BC,得BD=DC,DF:BF=2:3,可求得,MD=6,ME=5,过M作BC的平行线.交EF于H,得EH=9-6=3.MH=4,推出,AB=4MH=16