A 12-foot ladder is leaning against a wall. The bottom of the ladder is 5 feet away from the bottom of the wall.

Approximately how high up the wall does the top of the ladder reach?

A.

2.4 feet

B.

7.0 feet

C.

13.0 feet

D.

10.9 feet

The answer is D. 10.9 feet

This is the right triangle and we can use the Pythagorean theorem.

The length of the ladder is actually the hypotenuse: c = 12 ft

The bottom of the ladder is: a = 5 ft

b = ?

c² = a² + b²

12² = 5² + b²

144 = 25 + b²

144 - 25 = b²

b² = 119

b = √119

b = 10.9 ft