Online Geometry Problem 736: Triangle, Altitude, Perpendicular, Angles, Cyclic Quadrilateral. Level: High School, Honors Geometry, College, Mathematics Education

The figure shows a triangle ABC with the altitude BH. HD is perpendicular to AB, and HE is perpendicular to BC. If angle ACB = 57 degrees, and angle CDH = 21 degrees, find the measure of the angle AEB.