Question

Алгебра.................

Answer 1

Ответ:

$1) \sin( - \frac{3\pi}{4} ) = - \frac{ \sqrt{2} }{2}$

$2) \cos( \frac{2\pi}{3} ) = - \frac{1}{2}$

$3)tg( - \frac{5\pi}{6} ) = \frac{ \sqrt{3} }{3}$

$4)ctg( - \frac{5\pi}{4} ) = - 1$

Answer 2

Ответ:

$-\frac{\sqrt{2}}{2}; \quad -\frac{1}{2}; \quad \frac{\sqrt{3}}{3}; \quad -1;$

Объяснение:

$sin(-\frac{3\pi}{4})=-sin(\frac{3\pi}{4})=-sin(\pi-\frac{\pi}{4})=-sin\frac{\pi}{4}=-\frac{\sqrt{2}}{2};$

$cos(\frac{2\pi}{3})=cos(\pi-\frac{\pi}{3})=-cos\frac{\pi}{3}=-\frac{1}{2};$

$tg(-\frac{5\pi}{6})=-tg(\frac{5\pi}{6})=-tg(\pi-\frac{\pi}{6})=-(-tg\frac{\pi}{6})=tg\frac{\pi}{6}=\frac{\sqrt{3}}{3};$

$ctg(-\frac{5\pi}{4})=-ctg(\frac{5\pi}{4})=-ctg(\pi+\frac{\pi}{4})=-ctg\frac{\pi}{4}=-1;$