Question

Решите неравенство: cos 3t меньше -(корень из 2) /2

Answer 1

$\cos3t\ \textless \ -\frac{\sqrt{2}}{2} \\ \frac{3\pi}{4}+2\pi n\ \textless \ 3t\ \textless \ \frac{5\pi}{4}+2\pi n, n\in \mathbb{Z} \\ \frac{\pi}{4}+\frac{2\pi n}{3}\ \textless \ t\ \textless \ \frac{5\pi}{12}+\frac{2\pi n}{3}$

Ответ

$t \in (\frac{\pi}{4}+\frac{2\pi n}{3};\frac{5\pi}{12}+\frac{2\pi n}{3}),n\in \mathbb{Z}$