Diagonals of parallelogram bisect each other. Therefore, PO = OR and SO = OQ In ΔPQS, PO is median. [∵ SO = OQ] Hence, ar(PSO) = ar(PQO) … (1) [∵ A median of a triangle divides it into two triangles of equal areas.] Similarly, in ΔPQR, QO is median. [∵ PO = OR] Hence, ar(PQO) = ar(QRO) … (2) And in ΔQRS, RO is median. [∵ SO = OQ] Hence, ar(QRO) = ar(RSO) … (3) From the equations (1), (2) and (3), we get ar(PSO) = ar(PQO) = ar(QRO) = ar(RSO) Hence, in parallelogram PQRS, diagonals PR and QS divide it into four triangles in equal area.