You can go online and read about it here:
https://www.google.ca/search?site=webhp&source=hp&q=pythagorean+theorem&oq=Pytha&gs_l=hp.1.1.0i131k1l3j0j0i131k1j0j0i131k1j0l3.5953.9244.0.12987.6.6.0.0.0.0.144.570.4j2.6.0....0...1c.1.64.hp..0.5.425.0..35i39k1.4J-foNTvGr4
