Answer:
15 ft
Step-by-step explanation: To solve this, you have to use the Pythagorean Theorem. The 25 ft is the hypotenuse, the longest side of the triangle. the building's height, 20 ft is one of the legs. The missing measurement is one of the other legs.
Pythagorean Theorem: A^2 + B^2 = C^2
A and B are legs and C is the hypotenuse.
Substitute the values:
20^2 + B^2 = 25^2
400+ B^2 = 625
625 - 400 = 225
225 = 15^2
