AD/BD=AE/EC,所以BD/AD=EC/AE
BD/AD+1=EC/AE+1
BD/AD+AD/AD=EC/AE+AE/AE
即AB/AD=AC/AE
AD:AB=AD:(BD+AD)=3;(2+3)=3:5
又有∠A=∠A,所以△ABC∽△ADE
DE/BC=AD/AB=3/5
AD/BD=AE/EC,所以BD/AD=EC/AE
BD/AD+1=EC/AE+1
BD/AD+AD/AD=EC/AE+AE/AE
即AB/AD=AC/AE
AD:AB=AD:(BD+AD)=3;(2+3)=3:5
又有∠A=∠A,所以△ABC∽△ADE
DE/BC=AD/AB=3/5