Let O be the center of the circle circumscribed around the acute triangle ABC, and let N be the midpoint of the arc ABC of this circle. On the sides AB and BC mark points D and E respectively, such that the point O lies on the segment DE. The lines DN and BC intersect at the point P, and the lines EN and AB intersect at the point Q. Prove that PQ⊥AC. geometryperpendiculararc midpointUkraine Correspondence