Question

A man, 1.5m tall, is on top of a building. He observes a car on the road at an angle of 75°. If the building is 30m, how far is the car from the building?​

Answer 1

The answer to this question is 8.44 m.

Explanation:

This problem is best illustrated in the photo below.

First, we must know that the angle stated in the problem is the angle of depression. Angle of depression is the angle between the horizontal and the line of sight of the observer. On the other hand, if the observer is looking upward, then the angle between the horizontal and his line of sight is called the angle of elevation.

Since we have the given angle of depression, we must use its complementary angle to solve for the distance of the car from the building.

Let x = complementary angle of 75°

y = distance of the car from the building

To solve for x,

To solve for y, we need to use a trigonometric function that will relate the adjacent of 15° and the opposite of 15°. Let us look at the mnemonics

SOH: Sine =

CAH: Cosine =

TOA: Tangent =

Therefore we must use the tangent function to solve for y.