Let ABCABC be an acute-angled triangle such that AB<ACAB < AC. Let DD be the point of intersection of the perpendicular bisector of the side BCBC with the side ACAC. Let PP be a point on the shorter arc ACAC of the circumcircle of the triangle ABCABC such that DP∥BCDP \parallel BC. Finally, let MM be the midpoint of the side ABAB. Prove that ∠APD=∠MPB\angle APD = \angle MPB.