The first question is to find $\displaystyle \Sigma^{b}_{n = 1}\frac{\sin n}{2^n}$ and the second being to find $\displaystyle \Sigma^{\infty}_{n = 1}\frac{\sin n}{2^n}$.

The thing is I'm not sure how to even begin these, so if someone could help me out that would be great. Thanks.