Cyclic quadrilateral
Revision as of 13:12, 18 June 2006 by IntrepidMath (talk | contribs)
A Cyclic Quadrilateral is a quadrilateral that can be inscribed in a circle. In a cyclic quadrilateral, opposite angles sum to 180 degrees. They frequently show up on Olympiad tests, and have many special properties such as Ptolemy's theorem.