### Perimeter of a Square #### Lesson Objective

In this lesson, we will learn about the perimeter of a square. In this lesson, we will:

• Learn about the perimeter of a square and the formula for finding its perimeter.
• See an example on using the formula to find a square's perimeter.
• See another example on using the formula to find the length of each side (edge) of a square.

The study tips and math video below will explain more. ### Study Tips #### Tip #1

A square has four right angles. It has four sides and all the sides have the same length.

Now, if the length of each side is L, the perimeter, P, of the square will be the sum of the length of each side. Hence:

P = 4L

The math video below will give more explanation on this. Also, we will see some examples on how to use this formula. ### Math Video #### Video on the perimeter of a square #### Math Video Transcript

PART 1

00:00:03.170
In this lesson, we will learn about the perimeter of a square.

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Consider this square. All the sides of this square have the same length, L.

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Knowing this, we can get the perimeter, P, by adding the length of each side.

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Hence, we have L, add with L, add with L here, and finally, add with another L.

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This gives, 4L.

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Therefore, the perimeter, P, of a square, is equals to 4L.

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Let's rewrite it here.

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Note that, in any calculation, when we found the value for P, it is important to include the unit.

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For example, if L is given in centimeter, the unit for the perimeter will be in centimeter as well.

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The next video will show some examples on using this formula. #### Video on the examples on using the formula P=4L #### Math Video Transcript

PART2

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After understanding the formula for the perimeter of a square, let's see some examples on using this formula.

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Find the perimeter of this square, when the length of each side is 3cm.

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We start with the formula for the perimeter of a square, P=4L.

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Since the length of each side is 3cm, we can substitute, L with 3.

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4, multiply with 3, gives 12.

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Hence, we have P=12.

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Now, this number is meaningless, unless we include the unit for it.

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Since the length is given in centimeter, the unit for the perimeter will also be in centimeter.

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Therefore, the perimeter of this square is 12 centimeter.

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Next example, given the perimeter of this square is 20ft, find the length of each side, L.

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We start with the formula for the perimeter of a square, P=4L.

00:01:19.070
Since the value of the perimeter is given, we can find the length of each side, by solving the equation for L.

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Here's how. Since the area is given as 20 ft, we can substitute P with 20.

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Now, we have, 4L=20.

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Let's rewrite this equation so that it looks neater.

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Here, to find L, we need to remove 4.

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We can do so, by dividing both sides of the equation with 4.

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This gives, L=20/4. 20 divided by 4, gives 5.

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Now, we have, L equals to 5. Note that, this number is meaningless, unless we include the unit for it.

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Since the perimeter is in feet, the length, L will also be in feet.

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Therefore, the length of each side is 5ft.

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That is all for this lesson. Try out the practice question to further your understanding.

### Practice Questions & More #### Multiple Choice Questions (MCQ)

Now, let's try some MCQ questions to understand this lesson better.

You can start by going through the series of questions on the perimeter of a square or pick your choice of question below.

• Question 1 on finding the perimeter of a square
• Question 2 on finding the length of each side of a square #### Site-Search and Q&A Library

Please feel free to visit the Q&A Library. You can read the Q&As listed in any of the available categories such as Algebra, Graphs, Exponents and more. Also, you can submit math question, share or give comments there. 