## Precalculus (6th Edition)

$\cos^{-1}(-2)$ does not exist.
Solve for radians, then convert to degrees. $y=\cos^{-1}x$ Domain:$[-1, 1]$ Range: $[0, \pi]$ Quadrants (unit circle): I and II -------- $y$ is the number from $[0, \pi]$ such that $\cos y=-2.$ But, such a y does not exist, as cosine can not be less than $-1$. More directly, $-2$ is not in the domain of $\cos^{-1}x$, so $\cos^{-1}(-2)$ does not exist.