How long the ladder in needed to reach a window 20 ft. highif its base rest 7 ft. from the base of the building?

To find the length of the ladder needed, you can use the Pythagorean theorem. The height of the window (20 ft) and the distance from the base of the building (7 ft) form a right triangle, where the ladder is the hypotenuse. Using the formula ( c = \sqrt{a^2 + b^2} ), where ( a = 20 ) ft and ( b = 7 ) ft, the length of the ladder ( c ) is calculated as ( c = \sqrt{20^2 + 7^2} = \sqrt{400 + 49} = \sqrt{449} \approx 21.2 ) ft. Thus, the ladder needs to be approximately 21.2 feet long.