Question

Реши неравенство 2cosx-√2<0

Answer 1

$2cosx-\sqrt{2}<0\Leftrightarrow cosx<\frac{\sqrt{2}}{2}\Rightarrow x\in \begin{bmatrix}\frac{\pi}{4}+2\pi k;\frac{7\pi}{4}+2\pi k\end{bmatrix},k\in \mathbb{Z}$