geometry
posted by M .
A 25foot ladder is placed against a vertical wall of a building. The base of the ladder is 7 feet from the base of the wall. If the top of the ladder slips 4 feet, how many feet will the base of the ladder slide?

a^2 + b^2 = c^2
a^2 + 7^2 = 25^2
a^2 + 49 = 625
a^2 = 625  49
a^2 = 576
a = 24
24  4 = 20
20^2 + b^2 = 25^2
400 + b^2 = 625
b^2 = 225
b = 15
15  7 = 8