## Calculus (3rd Edition)

(b) $\cos^{-1}2$ is not defined because $2$ is not in its domain, which is $[-1, 1]$ (c) $\csc^{-1}(1/2)$ is not defined because $\frac{1}{2}$ is not in its domain, which is $|x|\geq1$. (a) and (d) are defined because the given values are in the domain of the functions.