# How do you evaluate arccos(2)?

$\arccos \left(2\right)$ is a meaningless expression.
The argument of the $\arccos$ function must be a value in the range $\left[- 1 , + 1\right]$;
that is, the argument of the $\arccos$ function must be a value that could be generated by $\cos \left(\theta\right)$ for some angle $\theta$.