Suppose the foot of a 12-foot ladder was placed 4 feet from a building how high up on the building would the top of the ladder reach

Use the pythagorean theorem.

The foot of the ladder is 4 feet away from the building (leg 1)

The height of the building is leg 2

The ladder, which would be at an angle, is 12 feet. So our hypotenuse would be 12. The equation for this would be a²+4²=12²

We can then begin to solve

a² + 16 = 144

a² = 128

a=11.31

So, our answer is: The top of the ladder reaches the building at 11.31 feet up