Question

If you place a 20ft ladder 4ft from the base of the wall, what is the angle measure of the ladder to the ground to the nearest degree.

Answer 1

Given:

Length of the ladder = 20 ft

Distance between base of the ladder and wall = 4 ft

To find:

The angle measure of the ladder to the ground to the nearest degree.

Solution:

Ladder is the hypotenuse of a right triangle. Here, we have,

Hypotenuse = 20 ft

Base = 4 ft

In a right angle triangle,

$\cos \theta=\dfrac{Base}{Hypotenuse}$

$\cos \theta=\dfrac{4}{20}$

$\cos \theta=\dfrac{1}{5}$

Taking cos inverse on both sides, we get

$\theta=\cos^{-1}\dfrac{1}{5}$

$\theta=78.46304^\circ$

$\theta\approx 78^\circ$

Therefore, the correct option is A.