Question

Calcule:
Cos 330°...... Cos 120°.....Cos 3pi/2......Cos 5pi/3......Cos 90°.....Cos pi......Cos 5pi/4......Cos 0

Answer 1

cos330°=cos30°

$= \frac{ \sqrt{3} }{2}$

Cos120°=-cos60°

$= - \frac{1}{2}$

$\cos( \frac{3\pi}{2} ) = 0$

$\cos( \frac{5\pi}{3} ) = \cos( \frac{\pi}{3} ) = \frac{1}{2}$

$\cos(90) = 0$

$\cos(\pi) = - 1$

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

$\cos(0) = 1$