P,B,Q,R lie on a circle
Source: Russia 2000 10.3
December 25, 2009
geometryparallelogramtrigonometrygeometric transformationreflectioncircumcircleangle bisector
Problem Statement
In an acute scalene triangle the bisector of the acute angle between the altitudes and meets the sides and at and respectively. The bisector of the angle intersects the segment joining the orthocenter of and the midpoint of at point . Prove that , , , lie on a circle.