  A quadrilateral is said to be rational if its four sides, the two diagonals
and the area are all expressible by rational numbers. The problem of
constructing rational quadrilaterals dates back to the seventh century when
Brahmagupta gave an elegant solution of the problem. In 1848 Kummer gave a
method of generating all rational quadrilaterals. In this paper we present an
alternative method of generating all rational quadrilaterals. For rational
cyclic quadrilaterals, we obtain a complete parametrization and for noncyclic
rational quadrilaterals, we give several parametrizations in terms of quadratic
and quartic polynomials. The parametrizations obtained in this paper are
simpler than the known parametrizations of rational quadrilaterals. We also
describe how further parametrizations of rational quadrilaterals may be
obtained.
