(a)[4]
Calculate the distance $AB$ between the two ships. Hence show that it rounds to $138$ km, correct to the nearest kilometre.
(b)[4]
The bearing of the coastguard station $C$ from ship $A$ is $146^\circ$. Calculate the bearing of ship $B$ from ship $A$.
(c)[2]
At noon, a lighthouse $L$ is $46.2$ km from ship $B$ on a bearing $021^\circ$. Ship $B$ sails north west. Calculate the distance ship $B$ must sail to be at its closest distance to the lighthouse.