Question 452573
The line of sight from a small boat to the light at the top of a 45-foot
 lighthouse built on a cliff 25 feet above the water makes a 39 degree angle with the water. 
To the nearest foot, how far is the boat from the cliff?
:
Let d = distance to the base of the cliff (side adjacent to 39 degree angle)
25 + 45 = 70'; height of lighthouse, side opposite 39 degree angle
:
Tan(39) = {{{70/d}}}
d = {{{70/tan(39)}}}
d = 86 ft from the base of the cliff
:
Distance from the boat to the cliff (c) itself which is 25' ft above the base, use pythag
c^2 = 25^2 + 86^2
c^2 = {{{sqrt(625 + 7396)}}}
c = 89.6 ft