The document discusses the Pythagorean theorem and distance formula. The Pythagorean theorem states that for a right triangle, the sum of the squares of the two legs equals the square of the hypotenuse (A2 + B2 = C2). It is used to calculate the length of the hypotenuse given the lengths of the two legs. The distance formula calculates the distance between two points by taking the square root of the sum of the squared differences between the x- and y-coordinates.