2011 Lusophon Mathematical Olympiad - Problem 5
Source: 2011 Lusophon Mathematical Olympiad - Problem 5
September 17, 2011
geometryrectanglesymmetrygeometric transformationparallelogramreflectionrotation
Problem Statement
Consider two circles, tangent at , both inscribed in a rectangle of height and width . A point moves counterclockwise around the circle on the left, and a point moves clockwise around the circle on the right. and start moving at the same time; starts at , and starts at , where is the point where the circle on the right intersects the top side of the rectangle. Both points move with the same speed. Find the locus of the midpoints of the segments joining and .