Answer:
12 ft
Explanation:
These circumstances describe a triangle with hypotenuse 13 ft and bottom side 5 ft. The vertical side (height above ground to top of ladder) is to be found. According to the Pythagorean Theorem,
5^2 + (vertical side)^2 = 13 ft = 169, and so
(vertical side) = sqrt( 169 - 25 ) = 144 (ft)
The top of the ladder is s 12 ft above the ground.