Question

ПОМОГИТЕ ПОЖАЛУЙСТА СРОЧНО

Answer 1

Ответ:

Применяем формулы приведения .

$\bf \displaystyle cos225^\circ =cos(180^\circ +45^\circ )=-cos45^\circ =-\frac{\sqrt2}{2}\\\\sin246^\circ =sin(180^\circ +60^\circ )=-sin\, 60^\circ =-\frac{\sqrt3}{2}\\\\cos(-150^\circ )=cos150^\circ =cos(180^\circ -30^\circ )=-cos30^\circ =-\frac{\sqrt3}{2}\\\\sin315^\circ =sin(270^\circ +45^\circ )=-cos45^\circ =-\frac{\sqrt2}{2}\\\\cos\frac{5\pi }{4}=cos(\pi +\frac{\pi }{4})=-cos\frac{\pi }{4}=-\frac{\sqrt2}{2}$    

$\bf \displaystyle cos(-\frac{4\pi }{3})=cos\frac{4\pi }{3}=cos(\pi +\frac{\pi }{3})=-cos\frac{\pi }{3}=-\frac{1}{2}\\\\sin(-\frac{5\pi }{3})=-sin\frac{5\pi }{3}=-sin(2\pi -\frac{\pi }{3})=sin\frac{\pi }{3}=\frac{\sqrt3}{2}$