Решите уравнение \(\cos 8x = \cos x\) . \(\frac{2\pi k}{9}; \frac{2\pi k}{7}, k \in Z\) \(\frac{2\pi k}{7}; \frac{2\pi}{9} + \frac{\pi k}{9}, k \in Z\) \(\frac{\pi k}{9}; \frac{2\pi k}{7}, k \in Z\) \(\frac{2\pi k}{9}; \frac{\pi}{7} + \frac{2\pi k}{7}, k \in Z\)

Задание

Решите уравнение \(\cos 8x = \cos x\) .

\(\frac{2\pi k}{9}; \frac{2\pi k}{7}, k \in Z\)
\(\frac{2\pi k}{7}; \frac{2\pi}{9} + \frac{\pi k}{9}, k \in Z\)
\(\frac{\pi k}{9}; \frac{2\pi k}{7}, k \in Z\)
\(\frac{2\pi k}{9}; \frac{\pi}{7} + \frac{2\pi k}{7}, k \in Z\)