在AB边上取AE=2/5AB,在AC边上取AF=1/5AC.则有,AP=AE+AF=AE+EP.AP/sinPEA=AP/sinBAC=EP/sinEAP,AP*sinBAP=EP*sinBAC.△PBC和△ABC的面积之比为1/2*AB*AP*sinBAP/1/2*AB*AC*sinBAC=EP*sinBAC/AC*sinBAC=1/5....