Answer
$-6$
Work Step by Step
As period of cotangent function is $\pi$, then
$$\cot \theta=\cot(\theta-\pi)=\cot(\theta-2\pi)$$
Hence,
$$\cot \theta+\cot(\theta-\pi)+\cot(\theta-2\pi)=\cot{\theta}+\cot{\theta}+\cot{\theta}=3\cot\theta=3\times(-2)=-6$$
