IMO 1987 LL MOR44

Let \theta1, \theta2, . . . , \thetan be real numbers such that sin \theta1 + \cdot \cdot \cdot +

imolonglistmathematicsolympiad

IMO 1987 LL MOR44

Origin: MOR

Problem

Let \theta1, \theta2, . . . , \thetan be real numbers such that sin \theta1 + \cdot \cdot \cdot + sin \thetan = 0. Prove that | sin \theta1 + 2 sin \theta2 + \cdot \cdot \cdot + n sin \thetan| \leq n2 .