Is there a relatively fast way of solving this?

If $\displaystyle f(i)=\frac{1+i+i^2+...+i^{11}}{1-i}$ which of the following statements are true?

(a) $\displaystyle f(i)=2+i$

(b) $\displaystyle Re[f(i)]=5$

(c) $\displaystyle Im[f(i)]=8$

(d) $\displaystyle f(i)=1-i$

(e) $\displaystyle f(i)=0$

Thanks for your help!