In a scalene triangle , and respectively denote the interior angles at vertixes and . The bisectors of these two angles meet the opposite sides of the triangle at points and , respectively. Prove that the acute angle between the lines and does not exceed . Proposed by Dusan Djukic
RS-SMO 2009
Serbian Mathematical Olympiad 2009.
The official paper in 1 language
Other problems
Find the smallest natural number which is a multiple of and whose sum of (decimal) digits equals Proposed by Milos Milosavljevic