取AC中点O,连接OE,OE为△ABC中位线故有AD∥OE∥BC,OE=(1/2)BC=(1/2)AD△AGF∽△OGEAG:OG=AF:OE=(1/3)AD:(1/2)AD=2/3AG:AO=2/5AG:AC=AG:(2AO)=1/5
等于4
等于4啊
