证明：（1）∵∠BAE=∠DAF，AB=AD，∠B=∠ADF=90°，∴△ABE≌△ADF，∴AE=AF，BE=DF．（2）∵AG为∠EAF的角平分线，∴∠EAG=∠FAG，又∵AE=AF，∴△AEG≌△AFG，∴EG=FG，∵FG=DG+FD，∴EG=BE+DG．
AD=ABADF,ABE全等BE=DF AGF，AGE全等EG=DG+FD=DG+BE
