AF平分∠BAC
证明:
∵AB=AC,∠BAD=∠CAE,∠AEC=∠ADB=90°
∴△ABD≌△ACE
∴AE=AD
∵AF=AF,∠AEF=∠ADF
∴△AEF≌△ADF
∴∠EAF=∠DAF
即AF平分∠BAC