Racquetball was invented by combining some of the rules from handball, racquetball, and paddleball. It was invented by Joe Sobek. Racquetball was made an official sport in 1952 under the name of "paddle rackets".
Pi wasn't invented so much as discovered. Pi is the ratio of a circle's circumference divided by the diameter. One could say that no one invented it, but that it was discovered. The Egyptians and the...