Which US President proved the Pythagorean theorem in a new way?

James A. Garfield, the twentieth President of the United States, discovered an original proof of the Pythagorean theorem. The proof is algebraic in nature and uses the formula for the area of a trapezoid. See the link below for details. Garfield is credited with an original proof of this famous theorem. Many of the presidents undoubtedly proved it in geometry class after studying their books.