Answer
(a) $3$.
(b) $-9$.
Work Step by Step
Given $f(\theta)=cot\theta$ (an odd function) with $f(a)=cot(a)=-3$, we have:
(a) $f(-a)=-f(a)=3$.
(b) $f(a)+f(a+\pi)+f(a+4\pi)=cot(a)+cot(a+\pi)+cot(a+4\pi)=3cot(a)=-9$.
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