证明：∵∠C+DAC=90°,∠BAD+∠DAC=90°∴∠C=∠BAD∵BE平分∠ABC∴∠ABE=∠CBE∵∠AGE=∠BAD+∠ABE,∠AEG=∠C+∠CBE∴∠AGE=∠AEG∴AG=AE∵BE平分∠ABC,EF⊥BC,EA⊥AB∴EA=EF=AG∵AD⊥BC,EF⊥BC∴AD//EF∵AG=EF∴AG...