Online Geometry Problem 21: Acute Triangle, Orthocenter, Circle, Diameter, Tangent, Collinear Points. Level: High School, Honors Geometry, College, Mathematics Education

The drawing shows an acute triangle ABC with the orthocenter H. The tangents from A to the circle with diameter BC touch the circle at M and N. Prove that M, H, N are collinear (passing through the same straight line).