Let ABC be a triangle with orthocenter H and ℓ a line that passes through H, and is parallel to BC. Let m and n be the reflections of ℓ on the sides of AB and AC, respectively, m and n are intersect at P. If HP and BC intersect at Q, prove that the parallel to AH through Q and AP intersect at the circumcenter of the triangle ABC. geometryreflectionconcurrencyconcurrentorthocenter