2009年12月1日 · Martin, sides of a triangle might be called "O", "H" and "A" when in reference to a Sine/Cosine/Tangent formula (SOH-CAH-TOA), however the Pythagorean Theorem is specifically: a² + b² = c² Where "a" and "b" are the sides of the triangle, and "c" is the hypotenuse.