IMO Shortlist 1996 problem G1
Kvaliteta:
Avg: 5,0Težina:
Avg: 5,0 Let be a triangle, and its orthocenter. Let be a point on the circumcircle of triangle (distinct from the vertices , , ), and let be the foot of the altitude of triangle from the vertex . Let the parallel to the line through the point meet the parallel to the line through the point at a point . Let the parallel to the line through the point meet the parallel to the line through the point at a point . The lines and intersect at some point . Prove that the lines and are parallel.
Izvor: Međunarodna matematička olimpijada, shortlist 1996