在△ABF和△ACE中,∠AFB = 90°= ∠AEC ,∠BAF = ∠CAE ,
所以,△ABF ∽ △ACE ,
可得：AB/AC = AF/AE .
在△AEF和△ACB中,∠EAF = ∠CAB ,AE/AC = AF/AB ,
所以,△AEF ∽ △ACB .