Problem

Source: IMO Shortlist 1992, Problem 11

Tags: trigonometry, geometry, Law of Sines, Triangle, IMO Shortlist, IMO Longlist



In a triangle $ ABC,$ let $ D$ and $ E$ be the intersections of the bisectors of $ \angle ABC$ and $ \angle ACB$ with the sides $ AC,AB,$ respectively. Determine the angles $ \angle A,\angle B, \angle C$ if $ \angle BDE = 24 ^{\circ},$ $ \angle CED = 18 ^{\circ}.$