Trigonmetry! Finding the distance of a ship from shore?

Question

HELP!! Can't seem to figure out this problem! Thanks..

A person in a small boat, offshore from a vertical cliff known to be 100 feet in height, takes a sighting of the top of the cliff. If the angle of elevation is found to be 30 degrees, how far offshore is the ship?

Answer 1

As the distance s are small, we will ignore Earth's curvature.

Tan 30 = 1/sqrt3

= 100'/distance

Distance = 100(sqrt3) = 173.20 feet

Answer 2

tan 30 / 1 = 100 / distance

Cross multiply

100 * 1

---------- = 173.2 feet

tan 30