orthocenter and circumcenter - IMO LongList 1992 USA4
Source:
September 2, 2010
geometrycircumcircleorthocenterCircumcenterIMO ShortlistIMO Longlist
Problem Statement
Suppose that points are located on sides , and , respectively, of triangle in such a way that triangle is similar to triangle . Prove that the orthocenter of triangle is the circumcenter of triangle