A triangle ABC with orthocenter H is inscribed in a circle O and a point D is on arc AC. DE is perpendicular to BC and DF is perpendicular to AC. EF cuts DH at M. (See the figure below). Prove that M is the midpoint of DH.
Geometry Problems Visual Index 1241-1250 Open Problems All Problems Triangles Circumcircle Altitude Orthocenter Midpoint Perpendicular lines View or Post a solution