A Ladder Equation

Question

A ladder leans at a 60 degree angle against a wall. The distance from the wall to the foot of the ladder is 4.6m. What is the length of the ladder?

Answer 1

The ladder is the hypotenuse of a right triangle since the wall and the ground form a right angle.

Since the ladder is at a 60° angle, and the side adjacent to that angle is 4.6 m we can use the definition of cosine to find the length of the ladder.

Cosine = Adjacent side/ Hypotenuse

cos 60° = 4.6/Hypotenuse

Hypotenuse = 4.6/cos 60°

So the length of the ladder is 4.6/cos 60°

(The cos of 60° is 1/2)