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f(sin x) = sin(17x) if f(cos x) = cos(17x) (2019 Auckland MO S1)

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November 15, 2021
trigonometryalgebra

Problem Statement

Function ff satisfies the equation f(cosx)=cos(17x)f(\cos x) = \cos (17x). Prove that it also satisfies the equation f(sinx)=sin(17x)f(\sin x) = \sin (17x).