Use Stokes' Theorem to evaluate $\oint_{C} \mathbf{F} \cdot d \mathbf{r}$
$$
\begin{array}{l}{\mathbf{F}(x, y, z)=-3 y^{2} \mathbf{i}+4 z \mathbf{j}+6 x \mathbf{k} ; C \text { is the triangle in the }} \\ {\text { plane } z=\frac{1}{2} y \text { with vertices }(2,0,0),(0,2,1), \text { and }(0,0,0)} \\ {\text { with a counterclockwise orientation looking down the pos- }} \\ {\text { itive } z \text { -axis. }}\end{array}
$$