An observer (O) spots a bird flying at a 55° angle from a line drawn horizontal to its nest. If the distance from the observer (O) to the bird (B) is 15,000 ft., how far is the bird (B) from its nest (N) ?

Build a right triangle where the horizontal distance from the observer to the nest is the adjacent leg, the angle is 55° and the distance from the observer to the bird (inside the nest) is the hypotenuse of the triangle, which is sthe unknown variable, x.

Then, cos (55°) = adjacent leg/hypotenuse = 15,000 ft / x⇒ x = 15,000 ft / cos (55°) = 26,152 ft