For 10 points, name this theorem which is stated as "A squared plus B squared equals C squared."
James Garfield used trapezoids to prove this result, which is also proven in Euclid's Elements. With integral values for its three variables, it gives rise to namesake "triples," which cannot be found for exponents greater than two, according to Fermat's Last Theorem. It is a special case of the cosine law, where the angle is ninety degrees. For 10 points, name this theorem which is stated as "A squared plus B squared equals C squared."
James Garfield used trapezoids to prove this result, which is also proven in Euclid's Elements.
{Pythagorean} theorem