Paris Pamfilos, Three maximal cyclic quadrangles,
Forum Geometricorum, 10 (2010) 99--107.
Abstract: We study three problems concerning the determination of the maximal
cyclic quadrangle under certain restrictions on its diagonals: (a) assuming
that one of the diagonals as well as the intersection point of the two diagonals
are fixed, (b) assuming that the location of the intersection point of the
two diagonals is fixed, and (c) assuming that the intersection point of the
diagonals is fixed and the diagonals intersect under a constant angle.