MathDB
Functional relation

Source: Finnish Mathematics Competition 2002, Final Round, Problem 1

November 14, 2011
functiontrigonometryalgebra unsolvedalgebra

Problem Statement

A function ff satisfies f(cosx)=cos(17x)f(\cos x) = \cos (17x) for every real xx. Show that f(sinx)=sin(17x)f(\sin x) =\sin (17x) for every xR.x \in \mathbb{R}.