Skip to content

On a necessary and sufficient cyclicity condition for a quadrilateral

Sergey Sadov

math.GMarXiv:math/0410234

Abstract

A convex quadrilateral with sides a,b,c,d, and diagonals p,q is cyclic iff abp-bcq+cdp-daq=0. This condition, in spite of its simplicity, appears to be unnoted and unexpectedly proof-resilient. We employ advanced methods of computer algebra and nonlinear analysis.

Create a lesson