Mathematics

Problem

Which one of the following correctly represents the general solution of the equation

\cos x = \cos \alpha

(where

\alpha

is a fixed real number)? a)

x = n\pi \pm \alpha,\; n\in\mathbb{Z}

x = n\pi + (-1)^n\alpha,\; n\in\mathbb{Z}

x = 2n\pi \pm \alpha,\; n\in\mathbb{Z}

x = 2n\pi + \alpha,\; n\in\mathbb{Z}