1. Вычислите: a) sin$$\frac{7\pi}{3}$$; B) tg $$(-\frac{13\pi}{6})$$; 6) cos(-$$\frac{5\pi}{4}$$); r) ctg 13,5$$\pi$$.

1. Вычислите:

a) $$sin\frac{7\pi}{3} = sin(2\pi + \frac{\pi}{3}) = sin \frac{\pi}{3} = \frac{\sqrt{3}}{2}$$.

б) $$cos(-\frac{5\pi}{4}) = cos(\frac{5\pi}{4}) = cos(\pi + \frac{\pi}{4}) = -cos \frac{\pi}{4} = -\frac{\sqrt{2}}{2}$$.

в) $$tg(-\frac{13\pi}{6}) = -tg(\frac{13\pi}{6}) = -tg(2\pi + \frac{\pi}{6}) = -tg \frac{\pi}{6} = -\frac{\sqrt{3}}{3}$$.

г) $$ctg 13.5\pi = ctg(\frac{27}{2}\pi) = ctg(13\pi + \frac{\pi}{2}) = ctg(\pi*13 + \frac{\pi}{2}) = ctg(\frac{\pi}{2}) = 0$$.

Ответ: a) $$\frac{\sqrt{3}}{2}$$; б) $$\frac{-\sqrt{2}}{2}$$; в) $$\frac{-\sqrt{3}}{3}$$; г) $$0$$.