Question

An 18-foot ladder is leaning against a vertical brick wall. The base of the ladder is 9 feet away from the wall.

Answer 1

A^2 + b^2 = c^2
a^2 + 9^2 = 18^2
a^2 + 81 = 324
a^2 = 243
a = 15.589 = 15.6 feet is the angle the ladder is at :)