K. R. S. Sastry, Construction of Brahmagupta n-gons,
Forum Geometricorum, 5 (2005) 119--126.
Abstract: The Indian mathematician Brahmagupta's contributions
to mathematics and astronomy are well known. His principle of adjoining Pythagorean
triangles to construct general Heron triangles and cyclic quadrilaterals
having integer sides, diagonals and area can be employed to appropriate Heron
triangles themselves to construct any inscribable n-gon, n > or = 3, that
has integer sides, diagonals and area. To do so we need a different description
of Heron triangles by families that contain a common angle. In this paper
we describe such a construction.