Answer
(a) $ -\frac{1}{3}$.
(b) $ 1$
Work Step by Step
Given $f(\theta)=sin\theta$ (an odd function) with $f(a)=sin(a)=\frac{1}{3}$, we have:
(a) $f(-a)=-f(a)=-\frac{1}{3}$.
(b) $f(a)+f(a+2\pi)+f(a+2\pi)=sin(a)+sin(a+2\pi)+sin(a+2\pi)=3sin(a)=1$