Curves & Motion · Medium problem

Two ships' positions at time $t \ge 0$ (in hours, with coordinates in nautical miles) are $\mathbf r_A(t) = (t,\ 0)$ and $\mathbf r_B(t) = (3t - 10,\ -t)$. Find the minimum distance ever between the two ships. Give an exact answer in simplest radical form.