P is the intersection point of diagonals of cyclic ABCD. The circumcenters of △APB and △CPD lie on circumcircle of ABCD. If AC \plus{} BD \equal{} 18, then area of ABCD is ? <spanclass=′latex−bold′>(A)</span>36<spanclass=′latex−bold′>(B)</span>281<spanclass=′latex−bold′>(C)</span>2363<spanclass=′latex−bold′>(D)</span>4813<spanclass=′latex−bold′>(E)</span>None