A force $\vec{F}=(6.00 \hat{\mathrm{i}}-4.00 \hat{\mathrm{j}}) \mathrm{N}$ acts on a particle with position vector $\vec{r}=(-3.00 \hat{\mathrm{i}}+1.00 \hat{\mathrm{j}}) \mathrm{m}$. Find (a) the torque about the origin acting on the particle and $(b)$ the angle between $\vec{r}$ and $\vec{F}$.