№2. Найдите значение выражения: 1) sin 405 2) cos(15π/4) 3) tg(11π/6) 4) cos² 22° - sin² 22°

1. \( \sin 405^{\circ} \) = \( \sin (360^{\circ} + 45^{\circ}) = \sin 45^{\circ} = \frac{\sqrt{2}}{2} \) 2. \( \cos \frac{15\pi}{4} = \cos (4\pi - \frac{\pi}{4}) = \cos (-\frac{\pi}{4}) = \cos \frac{\pi}{4} = \frac{\sqrt{2}}{2} \) 3. \( \tan \frac{11\pi}{6} = \tan (2\pi - \frac{\pi}{6}) = \tan(-\frac{\pi}{6}) = -\tan \frac{\pi}{6} = -\frac{\sqrt{3}}{3} \) 4. \( \cos^2 22^{\circ} - \sin^2 22^{\circ} = \cos (2 \cdot 22^{\circ}) = \cos 44^{\circ} \) Ответ: 1) \( \frac{\sqrt{2}}{2} \) 2) \( \frac{\sqrt{2}}{2} \) 3) \( -\frac{\sqrt{3}}{3} \) 4) \( \cos 44^{\circ} \)