IMO 1974 LL CZS12
A circle K with radius r, a point D on K, and a convex
IMO 1974 LL CZS12
Origin: CZS
Problem
A circle K with radius r, a point D on K, and a convex angle with vertex S and rays a and b are given in the plane. Construct a parallelogram ABCD such that A and B lie on a and b respectively, SA + SB = r, and C lies on K.