Evaluate the line integral
int_C mathbf{F}cdot dmathbf{r}, where mathbf{F}(x,y,z) = xmathbf{i} - 3ymathbf{j} - 2zmathbf{k}
and C is given by the vector function mathbf{r}(t) = langle sin t, cos t, t angle, quad 0le t le 3pi/2.