Perimeter of a rectangle is the total length of its sides. The opposite sides of a rectangle are congruent.

P = a + b + a + b

Where *P* is the perimeter, *a* is the shorter side, and *b* is the longer side.

Example:

If *a = 3* and *b = 5* then:

P = 3 + 5 + 3 + 5 = 16