Draw a sketch in each question leave the answer in surd form with rational denominator

Question

From the top of a tower, the angle of depression of a boat is 30degree. If the tower is 20m high how far is the boat from the foot of the tower

Answer 1

if you drew the sketch, and reviewed your basic trig functions, you can see that

20/x = tan30°

Answer 2

Make a sketch and using the basic trig ratios, which you MUST learn, .....
x/20 = tan30° , where x is the distance between the boat and the tower along the horizontal.
= 20tan30° = .....

Answer 3

oops, read the angle wrong,
use oobleck's solution