MathDB
Unit square cut into m quadrilaterals inequality

Source: Baltic Way 2009

November 27, 2010
inequalitiesgeometrygeometry proposed

Problem Statement

A unit square is cut into mm quadrilaterals Q1,,QmQ_1,\ldots ,Q_m. For each i=1,,mi=1,\ldots ,m let SiS_i be the sum of the squares of the four sides of QiQ_i. Prove that S1++Sm4S_1+\ldots +S_m\ge 4