MathDB
find the size of an angle, a nice problem proposed by Greece

Source: bmo 1991

April 23, 2007
geometrygeometric transformationreflectionparallelogramtrapezoidgeometry proposed

Problem Statement

Let ABCABC be an acute triangle inscribed in a circle centered at OO. Let MM be a point on the small arc ABAB of the triangle's circumcircle. The perpendicular dropped from MM on the ray OAOA intersects the sides ABAB and ACAC at the points KK and LL, respectively. Similarly, the perpendicular dropped from MM on the ray OBOB intersects the sides ABAB and BCBC at NN and PP, respectively. Assume that KL=MNKL=MN. Find the size of the angle MLP\angle{MLP} in terms of the angles of the triangle ABCABC.