Solution: The angles are $30^\circ$, $60^\circ$, and $90^\circ$. Using the Law of Sines: $\frac5\sin 30^\circ = \fracc\sin 90^\circ$. Since $\sin 30^\circ = 0.5$ and $\sin 90^\circ = 1$, $c = \frac50.5 = 10$ km. - AMAZONAWS