证明:(1)∵AD是∠BAC的平分线,DE⊥AB,DC⊥AC,
∴DE=DC,
又∵BD=DF,
∴Rt△CDF≌Rt△EBD(HL).
∴CF=EB;
(2)∵AD是∠BAC的平分线,DE⊥AB,DC⊥AC,
∴△ADC≌△ADE,
∴AC=AE,
∴AB=AE+BE=AC+EB=AF+CF=EB=AF+2EB.
证明:(1)∵AD是∠BAC的平分线,DE⊥AB,DC⊥AC,
∴DE=DC,
又∵BD=DF,
∴Rt△CDF≌Rt△EBD(HL).
∴CF=EB;
(2)∵AD是∠BAC的平分线,DE⊥AB,DC⊥AC,
∴△ADC≌△ADE,
∴AC=AE,
∴AB=AE+BE=AC+EB=AF+CF=EB=AF+2EB.