A fixed ratio
Source: Iran 3rd round 2012-Geometry exam-P1
September 20, 2012
ratiogeometrycircumcircletrigonometryparallelogramgeometry proposed
Problem Statement
Fixed points and are on a fixed circle and point varies on this circle. We call the midpoint of arc (not containing ) and the orthocenter of the triangle , . Line intersects circle again in . Tangent in to circumcircle of triangle intersects line and circle again in and respectively. Prove that the value of is constant.Proposed by Mehdi E'tesami Fard