Answer
$135^o$
Work Step by Step
RECALL:
$y=\cot^{-1}{x}\longrightarrow \cot{y}=x$, and $0 \lt y\lt 180^o$
Thus,
$\theta=\cot^{-1}{(-1)}\longrightarrow \cot{\theta}=-1$
The cotangent function is negative in the second and fourth quadrants.
Note that $\cot{135^o} = -1$
Therefore, solving the equation above gives
$\theta = 135^o$
