College Algebra & Trigonometry, 2018a

370 CHAPTER 8. RIGHT TRIANGLE TRIGONOMETRY
Again, the angle of elevation will be equal to the corresponding angle of depression,
so we can use the triangle as seen below to solve the problem:
34 ◦
34 ◦
d
125 ft.
In this problem
tan 34 ◦ = 125
d
Multiply on both sides by d
d ∗ tan 34 ◦ = 125
Then divide on both sides by tan 34 ◦
d tan 34 ◦
tan 34 ◦ = 125
tan 34 ◦
d ≈ 185.32
Example 3
Sometimes a problem involves both an angle of elevation and an angle of depression.
From the roof of a house 20 feet off the ground, the angle of elevation of the top
of an apartment building is 63 ◦ and the angle of depression to the base of the
building is 24 ◦ . How far away from the house is the apartment building? How
tall is the apartment building?