Art of Problem Solving
AoPS Online
Math texts, online classes, and more
for students in grades 5-12.
Visit AoPS Online ‚
Books for Grades 5-12 Online Courses
Beast Academy
Engaging math books and online learning
for students ages 6-13.
Visit Beast Academy ‚
Books for Ages 6-13 Beast Academy Online
AoPS Academy
Small live classes for advanced math
and language arts learners in grades 2-12.
Visit AoPS Academy ‚
Find a Physical Campus Visit the Virtual Campus

Ptolemy's Inequality

Revision as of 15:06, 20 June 2006 by Puuhikki (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Ptolemy's inequality for a convex quadrilateral ABCD states that AB·CD + BC·DA ≥ AC·BD with equality iff ABCD is a cyclic quadrilateral.

Retrieved from "https://artofproblemsolving.com/wiki/index.php?title=Ptolemy%27s_Inequality&oldid=3466"