2 Perimeter Perimeter is the distance around the outside of a figure. The perimeter of a rectangle is derived by adding all four sides. Since the two lengths are equal, and the two widths are equal, then it can be written as P = 2l + 2w.For squares, the perimeter is found the same way (add all 4 sides). Since all sides are the same, however, you can use the formula P = 4s.
3 P = 2w + 2l P = 2(5) + 2(18) P = 10 + 36 P = 46 cm Example 18 cm 5 cm Perimeter results in regular units, not square units.P =P = 46 cm