Prove that bisectors of pair of VOA are in same line

TO PROOVE:-BISECTER OF VOA IS STRAIGHT LINE.DRAW TWO STRAIGHT LINE AB AND CD WHICH CUTS EACH OTHER AT O .Now draw the bisecter PO of angle AOC and bisecter OQ of angle BOD.Now we have to proove PQ is a straight line.From the question each side is bisected so other vertically opposite angle formed is also equal.if vertically opposite angle is equal then PO and OQ is in Stright line.