Question

If angle $\theta =-{60}^o$, find the value of $\cos \theta$.

Answer 1

Given, $\theta =-{60}^o$ ....(given)
$\therefore \cos \theta =\cos (-{60}^o)$
$=\cos {60}^o$ ......$[\because \cos (-\theta )=\cos \theta ]$
$=\frac{1}{2}$