2) cos x = √3 2 7) cos 2x = √2 2

• \(x = \pm arccos \frac{\sqrt{3}}{2} + 2\pi n\)
• \(x = \pm \frac{\pi}{6} + 2\pi n\)

Ответ: \(x = \pm \frac{\pi}{6} + 2\pi n\)

• \(2x = \pm arccos \frac{\sqrt{2}}{2} + 2\pi n\)
• \(2x = \pm \frac{\pi}{4} + 2\pi n\)
• \(x = \pm \frac{\pi}{8} + \pi n\)

Ответ: \(x = \pm \frac{\pi}{8} + \pi n\)