Question

A lighthose beacon is 140 meters above sea level,The waters around it bound in rocks as far as 100 meters from the base of the lighthouse.An observer on the deck of a ship 7 meters above sea level finds that the angle of elevation of the beacon is 30°,How many meters is the ship clear of the rocks?

Answer 1

tan 30= 140 / d

so
d = 140 / tan 30 = 140 / 0.577 = 243 meters total away from house
so
243 - 100 = 143 meters