Perimeter of a parallelogram

The perimeter of a parallelogram is the sum of the lengths of all 4 sides of the parallelogram. A parallelogram is a figure that is similar to a rectangle but has two opposite sides that are skewed, see the figure below. However, always two and two sides have the same length. Denote the lengths of the two different sides by a and b. Then the perimeter of the parallelogram, denoted by o, is equal to

$$\Large o = 2\cdot a + 2\cdot b$$

The following parallelogram has side lengths equal to a = 4, $b = \sqrt{5}$, so the circumference will be equal to

$$\Large o = 2\cdot4+2\cdot\sqrt5=8+2\sqrt5$$