证明:∠EAB=(1/2)∠BAF; ∠BAD=(1/2)∠BAC.则:
∠EAB+∠BAD=(1/2)*(∠BAF+∠BAC)=90度;,即∠EAD=90度,所以,DA⊥AE;
又AB=AC,AD平分∠BAC,则:∠ADB=90度;
又∠BEA=90度,故四边形ADBE为矩形,得AB=DE.(矩形对角线相等)
证明:∠EAB=(1/2)∠BAF; ∠BAD=(1/2)∠BAC.则:
∠EAB+∠BAD=(1/2)*(∠BAF+∠BAC)=90度;,即∠EAD=90度,所以,DA⊥AE;
又AB=AC,AD平分∠BAC,则:∠ADB=90度;
又∠BEA=90度,故四边形ADBE为矩形,得AB=DE.(矩形对角线相等)