Use the arc-length formula to find the radius of a circle given a central angle, $\displaystyle \theta=\frac{{{7}\pi}}{{4}}$, that subtends the arc-length, $\displaystyle {s}={22}$.

(i)  $\displaystyle {r}=$  exactly. 

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