Rectangle Perimeter Formula

The formula for perimeter of a rectangle is given as:

P = 2(l + w)

Where P is the perimeter, l is the length, and w is the width.

Perimeter of a Rectangle Example Problems

Let's work through a couple of example problems together to practice finding the perimeter of a rectangle.

Example Problem 1

Find the perimeter of a rectangle with a length of 12 and width of 5.

Solution:

1. The length and width are given to us. Let's plug the given dimensions into the formula.
2. P = 2(l + w) = 2(12 + 5)
3. P = 2(17) = 34
4. The perimeter of the rectangle is 34.

Example Problem 2

A rectangle has a perimeter of 15 and a length of 5. What is the width?

Solution:

1. Let's plug the given dimensions into the formula, then isolate w to find the width.
2. P = 2(l + w) → 15 = 2(5 + w)
3. 15 = 10 + 2w
4. 5 = 2w
5. w = 2.5
6. The width of the rectangle is 2.5.