Inequality for the incircle
Source: French TST 2004, pb. 5; 16th KMO #4
May 25, 2004
inequalitiesgeometryincentertrigonometryinradiusperimetercyclic quadrilateral
Problem Statement
Let , , and be the points where the incircle of a triangle touches the sides , , and , respectively.
Prove the inequality .