Home

Algebra and Pre-Algebra Lessons

Algebra 1 | Pre-Algebra | Practice Tests | Algebra Readiness Test

Algebra E-Course and Homework Information

Algebra E-course Info | Log In to Algebra E-course | Homework Calculator

Formulas and Cheat Sheets

Formulas | Algebra Cheat Sheets
» » Area Formula

Do You Need Help Interpreting an Area Formula?

Area is the number of square units inside of a shape. We typically find the area of a shape that is two dimensional (like a floor, or a piece of carpet, or a piece of land).

Since the area is measuring the number of square units inside of the shape, the units must be written as squared units (ex: cm2).

Below you will find the area formula for several different geometric shapes. In addition to the formula, you will find an example. This will help you to better understand the formula.

Many of the area formulas require you to know the height of the shape.

The height of the shape is always the distance from the top of the shape to the bottom. The height must be a straight, vertical line.


Keep this page handy as you study formulas and solve real world problems throughout your algebra studies!





Area of a Square


A square has 4 sides that are all exactly the same size. Therefore, finding the area is pretty easy! Since the area of a square or rectangle is length x width, we can just square the length of the side! Take a look!



formula for area of a square





Area of a Rectangle


A rectangle is a 4 sided figure with two pairs of parallel lines. Each set of parallel lines has the same length. To find the area of a rectangle we are going to multiply the length x the width.

formula for area of a rectangle





Area of a Parallelogram


A parallelogram is another 4 sided figure with two pairs of parallel lines. To find the area of a parallelogram, we will multiply the base x the height. Let's look at the formula and example.

formula for area of a parallelogram


Notice that we did not use the measurement of 4m. 4m did not represent the base or the height, therefore, it was not needed in our calculation.







Area of a Trapezoid


A trapezoid is a 4 sided figure formed by one pair of parallel sides. This area formula is a little more complicated. Study the example carefully!


Take note that the bases of a trapezoid are always the parallel lines.


formula for area of a trapezoid





Area of a Triangle


A triangle is a 3 sided figure. There are several different types of triangles. You must be careful when trying to locate the height of the triangle. Remember the height of the shape must be a straight, vertical line.

formula for area of a triangle

Again, notice that we did not need to use the measurement of 11cm. 11cm did not represent the base of the triangle, nor did it represent the height.

** You will not always need to use every measurement that is given in the problem.






Area of a Circle


A circle, of course, has no straight lines. We use pi (3.14) when we calculate the area of a circle.

formula for area of a circle




What Would Happen if We Were Given the Diameter of the Circle and Asked to Find the Area?


If you are given the diameter of a circle (which is the distance across the circle - through the center), then you would divide the diameter in half. 1/2 of the diameter = the radius.



area formula for a circle




Don't forget that the area is a measurement of the inside space of a two dimensional figure. We are measuring how many "square units" fit on the inside.

I hope that these formulas have helped you to solve your algebra problems. Good luck!




Return from Area Formula to Algebra Formulas


Like This Page?



Comments

We would love to hear what you have to say about this page!

Top of the Page

Follow Algebra-Class




Recommend Algebra Class




Algebra Class E-course Members

Username:
Password:

Sign Up for Algebra Class E-courses

Click here to retrieve a lost password.

Search This Site

Custom Search

Having Trouble with Your Homework?

algebrator


Algebra Class Courses

algebra ecourse

pre algebra ecourse


Algebra Class
Most Popular Pages

algebra practice test

algebra cheat sheets

algebra formulas


Connect and Follow Algebra Class



Copyright © 2009-2014 Karin Hutchinson ALL RIGHTS RESERVED