MathDB
Moldova NMO, 2007, XI Grade, Problem 4

Source: maybe this is Calculus..

March 3, 2007
functionalgebra unsolvedalgebra

Problem Statement

The function f:RRf: \mathbb{R}\rightarrow\mathbb{R} satisfies f(cotx)=sin2x+cos2xf(\textrm{cot}x)=\sin2x+\cos2x, for any x(0,π)x\in(0,\pi). Find the minimum and maximum value of g:[1;1]Rg: [-1;1]\rightarrow\mathbb{R}, g(x)=f(x)f(1x)g(x)=f(x)\cdot f(1-x).