Question

Вычислите: а) 2sin60° + ctg ( - π/6) б) cos 7π/4 + tg540°

Answer 1

1)

$\displaystyle 2sin(60)+ctg(-\frac{\pi}{6})=2*\frac{\sqrt{3}}{2}- ctg(\frac{\pi}{6})=\sqrt{3}-\sqrt{3}=0$

2)

$\displaystyle cos(\frac{7\pi}{4})+tg(540)=cos(\pi-\frac{\pi}{4})+tg(360+180)=\\\\=cos(\frac{\pi}{4})+tg(\pi)=\frac{\sqrt{2}}{2}+0=\frac{\sqrt{2}}{2}$