(a)[2]
The boat departs from $A$ at $10\ 25$ and moves with an average speed of $15\text{ km/h}$. At what time will the boat reach $B$?
(b)[4]
The bearing of $B$ from $A$ is $056^\circ$. $B$ lies $2\text{ km}$ due west of $C$. Calculate $AC$.
(c)[2]
Point $C$ is at the foot of the cliff. Point $D$, the top of the cliff, is vertically above $C$. $DC$ is perpendicular to $BC$ and $DC = 105\text{ m}$. Calculate the angle of elevation of $D$ from $B$.