The document discusses the Pythagorean theorem and distance formula. The Pythagorean theorem states that the sum of the squares of the legs of a right triangle equals the square of the hypotenuse. It provides an example of using the theorem to solve for the length of the hypotenuse. The distance formula is used to find the distance between two points in a plane by treating them as the legs of a right triangle and using the Pythagorean theorem. It provides an example of using the distance formula to solve for the distance between two points.