The document explains the Pythagorean theorem and distance formula. The Pythagorean theorem states that a^2 + b^2 = c^2 and is used to find the length of the hypotenuse of a right triangle given the lengths of the other two sides. The distance formula finds the distance between two points (x1, y1) and (x2, y2) by taking the square root of (x1 - x2)^2 + (y1 - y2)^2. Examples are provided to demonstrate how to apply each formula.