Suppose $\vec{F} = (2 x - 4 y) \vec{i} + (x + 2 y) \vec{j}$. Use Stokes' Theorem to make the following circulation calculations.

(a) Find the circulation of $\vec{F}$ around the circle $C$ of radius $9$ centered at the origin in the xy-plane, oriented clockwise as viewed from the positive z-axis.
Circulation = $\displaystyle \int_C \vec{F} \cdot d\vec{r}$ =

(b) Find the circulation of $\vec{F}$ around the circle $C$ of radius $9$ centered at the origin in the yz-plane, oriented clockwise as viewed from the positive x-axis.
Circulation = $\displaystyle \int_C \vec{F} \cdot d\vec{r}$ =