# How do you solve and find the value of cos^-1(-1)?

Oct 26, 2016

You can call v its value... Also remember that ${\cos}^{-} 1$ is the same as $\arccos$...

So, let's say that:

$v = \arccos \left(- 1\right)$

If this is the case, then:

$\cos \left(v\right) = - 1$

It turns out that:

$\cos \left(\pi\right) = - 1$

Therefore, $v = \pi$ and this is your answer. You can check this result by looking at the $y = \arccos x$ graph below. When $x = - 1$, $y = \pi$ which confirms that the result we've obtained is correct.

graph{y=arccosx [-10, 10, -5, 5]}