MathDB
Maximization of a sum of sines

Source: Czech and Slovak Olympiad 1983, National Round, Problem 1

April 10, 2020
maximizationalgebranational olympiad

Problem Statement

Let nn be a positive integer and k[0,n]k\in[0,n] be a fixed real constant. Find the maximum value of i=1nsin(2xi)\left|\sum_{i=1}^n\sin(2x_i)\right| where x1,,xnx_1,\ldots,x_n are real numbers satisfying i=1nsin2(xi)=k.\sum_{i=1}^n\sin^2(x_i)=k.