Let ABC be an acute-angled triangle with AB=AC, and let I and O be its incenter and circumcenter, respectively. Let the incircle touch BC,CA and AB at D,E and F, respectively. Assume that the line through I parallel to EF, the line through D parallel toAO, and the altitude from A are concurrent. Prove that the concurrency point is the orthocenter of the triangle ABC. Petar Nizic-Nikolac, Croatia incentergeometryCircumcenterorthocenter