Complete question is;
A 21 ft ladder is leaning against a tall wall with the foot of the ladder placed at 7 feet from the base of the wall and the angle of elevation is?
Answer:
θ = 70.5°
Explanation:
The angle of elevation simply means the angle that the ladder makes with the ground. Let's call this angle θ.
I've attached a diagram showing the triangle made by this ladder and the wall.
From the attached diagram, we can see the triangle formed by the ladder and the wall.
We can find the angle of elevation θ from trigonometric ratios.
Thus;
7/21 = cos θ
cos θ = 0.3333
θ = cos^(-1) 0.3333
θ = 70.5°