posted by Ashley .
It is 4.7km from Lighthouse A to Port B. The bearing of the port from the lighthouse is N73E. A ship has sailed due west from the port and its bearing from the lighthouse is N31E. How far has the ship sailed from the port?
If the ship has sailed to point C,
angle A = 73°-31° = 42°
angle B = 17°
so, angle C is 121°
the distance AC is side a, where
a/sin42° = 4.7/sin121°
a = 3.67