Perimeter Formulas
Introduction
This page contains the formula for area of a:
Examples are given to show you how to use the formulas.
![](https://www.mathexpression.com/images/xgrade-3-100.png.pagespeed.ic.n8aLjvQslv.png)
Have fun practicing perimeter questions by downloading our free Zapzapmath Home Grade 3 app and playing Fency Farm:
Apple App Store (iOS) |
Google Play (Android)
Square
Formula
The lesson on the perimeter of a square will provide the explanation and examples needed to understand this formula. Here's the summary:
All the sides (edges) of a square have the same length. If each side has the length L, the formula for the preimeter P will be:
![square with the sides L](https://www.mathexpression.com/image-files/square.png)
Example
Given a square where the side lengths are 3cm. Find the perimeter of this square.
![Using the formula for the perimeter of a square](https://www.mathexpression.com/image-files/xperimeter-square-l-3.png.pagespeed.ic.2VgpkCvmno.png)
Rectangle
Formula
The lesson on the perimeter of a rectangle will cover the basics needed to use this formula. Here's a short summary:
If a rectangle has the length l and the width w, the perimeter P, will be:
![formula for the perimeter of a rectangle](https://www.mathexpression.com/image-files/xperimeter-rectangle.png.pagespeed.ic.eCGw8wy2KW.png)
![rectangle with width w and length l](https://www.mathexpression.com/image-files/xrectangle-lw.png.pagespeed.ic.L9dHXQsp_S.png)
Example
Given a rectangle with the length of 5ft and the width of 3ft. Find its perimeter.
![Using the formula for the perimeter of a rectangle](https://www.mathexpression.com/image-files/xcalc-peri-rectangle.png.pagespeed.ic.Nee2EPjZYq.png)
Triangle
Formula
The lesson on the perimeter of a triangle will explain the basics behind this formula. Here's the summary:
For a triangle with the side lengths of a, b and c, its perimeter P, will be:
![formula for the perimeter of a triangle](https://www.mathexpression.com/image-files/xtriangle-perimeter-a-b-c.png.pagespeed.ic.OyU9j7Wl9t.png)
![a circle with the radius r](https://www.mathexpression.com/image-files/triangle-sides-a-b-c.png.pagespeed.ce.tnM9XOaBtR.png)
Example
Given a triangle with the side lengths of 3cm, 4cm and 5cm. Find the perimeter of the triangle.
![Using the formula for the perimeter of a triangle](https://www.mathexpression.com/image-files/xcalc-perimeter-triangle.png.pagespeed.ic.MbISbDX7t4.png)
Parallelogram
Formula
The lesson on the perimeter of a parallelogram will explain the basics. Here's the summary:
For a parallelogram with the side lengths of a and b, its perimeter P, will be:
![formula for the perimeter of a parallelogram](https://www.mathexpression.com/image-files/xperimeter-parallelogram-2.png.pagespeed.ic.w9olyWbpzF.png)
![a parallelogram with the base b and height h](https://www.mathexpression.com/image-files/xparallelogram-b-h.png.pagespeed.ic.Qjs116tHbS.png)
Example
Given a parallelogram with the side lengths of 8 inches and 6 inches. Find the perimeter of this parallelogram.
![Using the formula for the perimeter of a parallelogram](https://www.mathexpression.com/image-files/xcalc-peri-parallelogram.png.pagespeed.ic.JdA9sa6a-R.png)
![](https://www.mathexpression.com/images/xgrade-3-100.png.pagespeed.ic.n8aLjvQslv.png)
Have fun practicing perimeter questions by downloading our free Zapzapmath Home Grade 3 app and playing Fency Farm:
Apple App Store (iOS) |
Google Play (Android)