In a parallelogram ABCD, the line drawn through a point P on AB; parallel to BC, meets AC at Q. The line through Q, parallel to AB meets AD at R. Then, APPB=
AQQC
ARRD
In Δ ACD,
QR || CD
AQQC=ARRD ..............(i)
In Δ ACB,
PQ || CB
AQQC=APPB ..............(i)
On comparing (i) & (ii), we get
APPB=ARRD ..............(iii)
Using result (i) & (ii) & (iii)
APPB=AQQC=ARRD