EMAT 6690

Summer 2003

Ptolemy' Theorem: Cyclic Quadrilateral

A cyclic quadrilateral is a qudrilateral that a circle can circumscribed so that it touches each vertex of the quadrilateral. The sum of the pair of opposite angles is 180. Of all quadrilateral the cyclic quadrilateral has the maximum area. If the four side are known the area can be obtained using Brahmagupta's formula.


This is not a cyclic quadrilateral.