Long before the invention of modern clamps and jigs, people used their intellect to create square corners. They did this by using the Pythagorean theorem, a geometric proof in which the square of the longest side of a right triangle equals the sum of the squares of the remaining sides. Woodworkers, carpenters, and engineers use this method to create square corners when dimensions exceed the realm of a standard framing square. By using a triangle with sides in exact multiples of 3, 4, and 5 (for example: 6, 8, and 10), you'll always get a square corner opposite the longest side.