Posted by anonymous on .
a 15 foot ladder is placed against a vertical wall of a building with the bottom of the ladder stand on level ground 12 feet from the base of the building. How high up the wall does the ladder reach?

math 
Ms. Sue,
a^2 + b^2 = c^2
a^2 + 12^2 = 15^2
a^2 + 144 = 225
a^2 = 81
a = 9