Perimeter of a rectangle

By the perimeter of a rectangle we mean the sum of the lengths of all four of its sides. A rectangle always has two pairs of equal sides; if all four sides are equal, it is a square. Let’s call the lengths of the two different sides a and b. Then the perimeter of the rectangle, which we write as P, is

$$P=2\cdot a+2\cdot b$$

The following rectangle has side lengths a = 5 and b = 2, so its perimeter is

$$P=2\cdot 5+2\cdot 2=14$$