Ptolemy's Inequality
Revision as of 14:25, 20 June 2006 by MCrawford (talk | contribs) (Ptolemy inequality moved to Ptolemy's Inequality: fixed name)
Ptolemy's inequality for a convex quadrilateral ABCD states that AB·CD + BC·DA ≥ AC·BD with equality iff ABCD is a cyclic quadrilateral.
