How was James Garfield a mathematician?

James Garfield, the 20th President of the United States, was also an accomplished mathematician. He is known for his work on a geometric proof of the Pythagorean theorem, which he published in 1876. Garfield's proof involved a trapezoid and demonstrated the relationship between the areas of different shapes, showcasing his analytical skills and deep understanding of mathematics. His contributions reflect his broader interests in education and intellectual pursuits beyond his political career.