Elementary algebra sign). One of the most well-known equations describes Pythagoras' law relating the length of the sides of a right angle triangle: This equation states that formula_44, representing the square of the length of the side that is the hypotenuse (the side opposite the right angle), is equal to the sum (addition) of the squares of the other two sides whose lengths are represented by formula_45 and formula_46. An equation is the claim that two expressions have the same value and are equal. Some equations are true for all values of the involved variables (such as formula_47); such equations are called
Pythagorean theorem used as a triangle "C" on its hypotenuse, and two similar right triangles ("A" and "B" ) constructed on the other two sides, formed by dividing the central triangle by its altitude. The sum of the areas of the two smaller triangles therefore is that of the third, thus "A" + "B" = "C" and reversing the above logic leads to the Pythagorean theorem a + b = c. ("See also Einstein's proof by dissection without rearrangement") The Pythagorean theorem is a special case of the more general theorem relating the lengths of sides in any triangle, the law of