Force $\vec{F}=(-8.0 \mathrm{~N}) \hat{\mathrm{i}}+(6.0 \mathrm{~N}) \mathrm{j}$ acts on a particle with position vector $\vec{r}=(3.0 \mathrm{~m}) \mathrm{i}+(4.0 \mathrm{~m}) \hat{j}$ What are
(a) the torque on the particle about the origin, in unit-vector notation, and
(b) the angle between the directions of $\vec{r}$ and $\vec{F} ?$