Question

The pilot of a traffic helicopter sights an accident at an angle of depression of 18°. The helicopter’s altitude is 1560 ft. What is the horizontal distance from the helicopter to the accident? Round to the nearest foot.

Answer 1

First, draw a diagram. The datum level would be where the helicopter is at up in the sky. An angle of depressing means that instead of rising, the angle start from the horizontal and moves clockwise. Then, you have the altitude which forms a vertical line opposite to the 18 degrees. You are to find x which is adjacent to the 18 degrees. Since the diagram forms a right angle, you use the tangent function:

tangent 18 = opposite / adjacent
tangent 18 = 1560 / adjacent
adjacent = 4,801.19

Thus, the horizontal distance is 4,801.19 ft