Answer:
30 ft
Step-by-step explanation:
This is a classic right triangle problem, where the length of the ladder represents the hypotenuse, where the ladder is lengthwise from the building is the base of the triangle, and what we are looking for is the height of the triangle. Pythagorean's Theorem will help us find this length.
so
1024 - 100 = y^2 and
y = 30.4 so 30 feet