∠BAE+∠DAF=90°,∠DAF+∠ADF=90°,∠ADF=∠BAE,∠B=∠DFA=RT∠,△ABE∽△DFA,AD/AE=AF/BE.
又在正方形ABCD中,AB=2.E是BC的中点,AE=√[2²+(2/2)²]=√5
所以2/√5=AF/(2/2),AF=2√5/5.
∠BAE+∠DAF=90°,∠DAF+∠ADF=90°,∠ADF=∠BAE,∠B=∠DFA=RT∠,△ABE∽△DFA,AD/AE=AF/BE.
又在正方形ABCD中,AB=2.E是BC的中点,AE=√[2²+(2/2)²]=√5
所以2/√5=AF/(2/2),AF=2√5/5.