Given :
A sailor is 30 m above the water in the crow's nest on a sailboat.
The sailor encounters an orca surface at an angle of depression of 15 degrees.
The crows nest is 20 m horizontally from the bow (front) of the boat.
To Find :
How far in front of the boat is the orca.
Solution :
Let, distance of boat front from the crow's nest is x.
So,

Hence, this is the required solution.