Question

решите уравнение cos (-x)=cos п/3

Answer 1

$\cos(-x) = \cos(x)\\\cos(-x) = \cos (\frac{\pi}{3}) \Leftrightarrow \cos(x) = \cos(\frac{\pi}{3}) \Rightarrow x = \pm\frac{\pi}{3} + 2\pi k, k \in \mathbb{Z}$