Answer
$cot^{-1}{-\frac{1}{2}}$ is defined.
$\cos^{-1}{-5}$ is undefined.
Work Step by Step
a) $cot^{-1}{-\frac{1}{2}}$ is defined because the value of cotanget lies between$-\infty$ and $\infty$.
b) $\cos^{-1}{-5}$ is not defined because the value of cos lies between -1 and 1.
