PART 1

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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.

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.

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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.