MathDB
Geometric inequality - angle bisector configuration

Source: Indian Postal Coaching 2012 Set 1 #1

September 19, 2013
inequalitiesinequalities unsolved

Problem Statement

Given a triangle ABCABC, the internal bisectors through AA and BB meet the opposite sides in DD and EE, respectively. Prove that DE \le (3 - 2\sqrt2)(AB + BC + CA) and determine the cases of equality.