Formula for Area
Introduction
This page contains the formula for area of a:
Examples are given to show you how to use the formulas.
Square
Formula
The lesson on the area of a square will explain the basics 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 area A will be:
![square with the sides L](https://www.mathexpression.com/image-files/square.png)
Example
Given a square where the length of each side (edge) is 5cm. Find the area of this square.
![Using the formula for the area of a square](https://www.mathexpression.com/image-files/xsquare-area-example.png.pagespeed.ic.EeTkc8M7HL.png)
Rectangular Solid
Formula
The lesson on the area 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, we can find the area A, by multiplying its width and its length together. Hence, we have:
![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 4ft and the width of 3ft. Find its area.
![Using the formula for the area of a rectangle](https://www.mathexpression.com/image-files/xrectangle-area-example.png.pagespeed.ic.eA2czieZa-.png)
Circle
Formula
The lesson on the area of a circle will explain to you on how to use this formula. Here's a short summary:
For a circle with the radius r, its area A, will be:
Where π is constant that is approximately equals to 3.14.
![a circle with the radius r](https://www.mathexpression.com/image-files/xcircle-with-radius-r.png.pagespeed.ic.BAQIhfxiWf.png)
Example
Given a circle with the radius 3cm. Find its area. Take π = 3.14.
![Using the formula for the area of a circle](https://www.mathexpression.com/image-files/xcircle-area-example.png.pagespeed.ic.DwKuchbYMI.png)
Parallelogram
Formula
The lesson on the area of a parallelogram will show you the basic ideas on using this formula. Here's a summary:
For a parallelogram with the base b and the height h, the area A, is given as:
![formula for the area of a parallelogram](https://www.mathexpression.com/image-files/xparallelogram-area-bh.png.pagespeed.ic.xfmqFY3K3m.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 base 5in and the height 3in. Find the area of this parallelogram.
![Using the formula for the area of a parallelogram](https://www.mathexpression.com/image-files/xparallelogram-area-example.png.pagespeed.ic.EXbxhtmYS7.png)
Triangle
Formula
The lesson on the area of a triangle will explain to you on how to use this formula.
Consider a triangle with the base b and height h, the area A, of this triangle is simply:
![formula for the area of a triangle](https://www.mathexpression.com/image-files/xtriangle-area-half-bh.png.pagespeed.ic.DEXFfn2Piy.png)
![triangle with the base b and height h](https://www.mathexpression.com/image-files/xtriangle-base-height.png.pagespeed.ic.uKWDlIfjs4.png)
Example
Given a triangle with the base 4cm and the height 2cm. Find its area.
![Using the area formula of a triangle](https://www.mathexpression.com/image-files/xtriangle-area-example.png.pagespeed.ic.nyffabNRkJ.png)
Trapezoid (Trapezium)
Formula
The lesson on the area of a trapezoid will explain the steps on using its formula for area. Here's the summary:
For a trapezoid with the height h and two parallel sides a and b, its area A, is given as:
![formula for the area of a trapezoid](https://www.mathexpression.com/image-files/xtrapezoid-area-formula.png.pagespeed.ic.ygtAhc9p0f.png)
![a trapezoid with the heigh h, and parallel sides of a and b.](https://www.mathexpression.com/image-files/xtrapezoid-with-label.png.pagespeed.ic.P4scXlqa5d.png)
Example
Given a trapezoid with the height of 4in, and two parallel sides of 2in and 3in respectively. Calculate its area.
![Using the formula for the area of a trapezoid](https://www.mathexpression.com/image-files/xcalc-trapezoid-area-2.png.pagespeed.ic.hSS8J9QCFp.png)