Use the arc-length formula to find length of the arc, $\displaystyle {s}$, subtended by the given central angle, $\displaystyle \theta={240}^{\circ}$, of a circle of radius, $\displaystyle {r}={19}$.

(i)  $\displaystyle {s}=$  exactly. 

(ii)  $\displaystyle {s}=$  approximated to the nearest tenth.