# How do you evaluate arccos (0)?

Jul 27, 2015

$\arccos 0$ means: find the angle that has a cosine of $0$

#### Explanation:

The $\cos$-function crosses the $0$ every ${180}^{o} \mathmr{and} \pi r a d$, beginning at ${90}^{o} \mathmr{and} \frac{\pi}{2} r a d$

So $\arccos \left(0\right) = {90}^{o} \pm k \cdot {180}^{o}$

Or $\arccos \left(0\right) = \frac{\pi}{2} \pm k \cdot \pi r a d$

Usually, you are asked to evaluate a function between certain limits, like ${0}^{o} \le x \le {360}^{o}$ or $0 < - x \le 2 \pi$
From the above you can find the values that fit.