证明:
∵CD⊥AB,BE⊥AC
∴∠AEB=∠ADC=90
∵AB=AC,∠BAE=∠CAD
∴△ABE≌△ACD (AAS)
∴AD=AE
∵AF=AF
∴△ADF≌△AEF (HL)
∴∠DAF=∠EAF
∴AF平分∠BAC