Question

обчисліть?
$sin \frac{13\pi}{6}$
$cos \frac{5\pi}{4}$
$tg \frac{7\pi}{6}$
$ctg \frac{5\pi}{3}$

Answer 1

$1)Sin\frac{13\pi }{6}=Sin(2\pi+\frac{\pi }{6})=Sin\frac{\pi }{6}=\frac{1}{2}\\\\2)Cos\frac{5\pi }{4}=Cos(\pi+\frac{\pi }{4})=-Cos\frac{\pi }{4}=-\frac{\sqrt{2} }{2}\\\\3)tg\frac{7\pi }{6}=tg(\pi+\frac{\pi }{6})=tg\frac{\pi }{6}=\frac{\sqrt{3} }{3}\\\\4)Ctg\frac{5\pi }{3} =Ctg(2\pi-\frac{\pi }{3})=-Ctg\frac{\pi }{3}=-\frac{\sqrt{3} }{3}$