MathDB
Gulf Mathematical Olympiad 2013 - Problem 2

Source: Gulf Mathematical Olympiad 2013

April 5, 2013
trigonometrygeometry unsolvedgeometry

Problem Statement

In triangle ABCABC, the bisector of angle BB meets the opposite side ACAC at B′B'. Similarly, the bisector of angle CC meets the opposite side ABAB at C′C' . Prove that A=60∘A=60^{\circ} if, and only if, BC′+CB′=BCBC'+CB'=BC.
Back to ProblemsView on AoPS