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What is a Perimeter in Math?

Discover what the perimeter is in math and how to calculate it. Learn different ways to measure the perimeter of shapes and find out when they're useful in real-life applications.
6 minutes
What is a Perimeter in Math?
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As a parent, you may be wondering what a perimeter is in math. The perimeter is the measurement of the distance around the outside of a shape. Students need to know what the perimeter is so they can figure out the size and dimensions of different things and areas.

In this guide, we’ll explore the concept of the perimeter in more detail and provide tips on how to help your child understand it better.

Perimeter is the distance around the outside of a shape

The perimeter is a basic math concept that can be used in real-world situations like cooking, gardening, and engineering.

While perimeter may seem intimidating at first, it's quite simple to understand. It’s defined as the total distance all around the edge of a shape or figure, which can be expressed in units such as centimeters or inches.

Depending on the shape, calculating the perimeter typically involves adding up multiple sides and/or curves to arrive at an answer. The perimeter allows us to quickly measure, compare, and determine the size of something without having to measure every side individually.

For example, if you are looking for the perimeter of a square, all you need to do is add up the length of each side. If the length of each side is 10 centimeters, then the perimeter would be 40 centimeters (10 + 10 + 10 + 10).

Other shapes may require more complicated calculations, but no matter what shape it is, the perimeter can help us determine the total length of the shape's sides. By knowing the perimeter, we can determine how much material (such as fabric, paper, or wood) is needed to construct a figure that has the given perimeter.

We can also use it to find the area of a shape by dividing the perimeter by four and finding the square root of that result.

How to find the perimeter of a rectangle 

Working out the perimeter of a rectangle is an easy task, but it is important to understand the correct way to do it. To find the perimeter of a rectangle, simply take the length and width measurements and add them together.

This will give you the total length around the four sides of your rectangle. It is important to remember that if you have a curved or irregular shape, this technique won't work, and you will need to approach it in a different way.

By understanding what measurements are involved and how they combine to reveal the perimeter, you will be able to quickly and accurately work out the answer you are looking for.

As an example, if you have a rectangle that is 4 cm wide and 7 cm long, the perimeter can be calculated by adding the length and width together. In this case, 4+7 = 11 cm, so your perimeter would be 11 cm.

When it comes to teaching children how to find the perimeter of a rectangle, a good place to start is by having them draw a shape on paper. Then have them measure and record the length and width of each side. Once they have all four sides measured, tell them to add up all the measurements to get the perimeter. You can also use a ruler to help measure the sides of the rectangle.

You can help kids learn more about perimeter by giving them simple word problems that ask them to find the perimeter of a rectangle. Have them read the problem, calculate it using the formula, and then explain how they arrived at their answer.

You can also ask them to draw the shape that is described in the problem, measure and record the sides, then add up all the measurements to arrive at their answer. This will help them get better at measuring and math, and it will also help them learn more about the perimeter.

What is the formula for finding the perimeter 

The formula for finding the perimeter of a rectangle is: P = 2(L + W). To apply it, you need to know the length (L) and width (W) of the rectangle, which can be measured with a ruler.

Then you must multiply the length by two and add it to twice the width; this will give you your answer. Knowing how to calculate the perimeter of a rectangle is incredibly useful in many everyday situations, such as working out how much fencing or walling material you will need for your garden.

Let's put that into practice. Suppose the length of a rectangle is 8 cm and the width is 4 cm. The perimeter would be calculated as follows:

P = 2(8 + 4)

P = 2(12)

P = 24 cm

So, the perimeter of our rectangle is 24 cm. It's also possible to calculate the perimeter of an irregular rectangle by adding the lengths of each side. This will give you the total length, and you can then double it to find out the perimeter.

How is the perimeter commonly used in math?

The perimeter is used to calculate the area of various shapes. For example, the formula for finding the area of a rectangle is A = l x w, where l and w are the length and width of the rectangle, respectively. The same principle applies to other shapes, such as triangles and circles. By knowing the perimeter of a shape, you can calculate its area more accurately.

Also, the perimeter can be used to solve problems with distance and circumference measurements.

For example, if you know the radius of a circle and its perimeter, you can use them to calculate the diameter. The perimeter can also be used to figure out the length of an arc, the area of a sector, and other similar measurements.

Finally, the perimeter can be used to find the area of an irregular shape, such as a triangle or polygon. By dividing the perimeter into equal lengths and then multiplying those lengths by one another, you can calculate the area of a shape with relative ease.

In short, the perimeter is a basic mathematical concept that can be used to measure shapes and figure out how big they are. It is often used in combination with other mathematical concepts, such as the area or radius of a shape, to solve more complex problems.

The perimeter can be used to solve problems in real life

The use of the perimeter in problem solving is far-reaching, as it is a vital tool for measuring and determining different parameters that are necessary for everyday life.

From calculating the size of building foundations to understanding how much fencing is needed to enclose an area, the perimeter has numerous practical applications across a range of sectors.

While the most common use of the perimeter concept is in the architectural field, its versatility also allows it to be applied to problems related to farming, constructing gardens and parks, measuring roads, and other areas.

In fact, any time a boundary around an enclosure needs to be set or measured accurately, the perimeter can be used as a rule of thumb to determine the necessary length.

Helping your child understand mathematics

Finding the perimeter of a rectangle is a simple matter of knowing the formula and plugging in the numbers. The formula is P = 2L + 2W, where P is the perimeter and L and W are the length and width of the rectangle.

For example, if a rectangle has a length of 4 inches and a width of 3 inches, then its perimeter would be calculated as follows:

P = 2(4) + 2(3) = 14 inches

If your child is struggling with math and needs extra help, contact us at Learner today to hire a tutor. We’ll be happy to pair you with someone who can provide the assistance you need to succeed.

Math tutoring is an effective way to build the confidence and skills you or your child need in order to excel. Don't hesitate to contact us at Learner today!

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About the author:

Mike developed his passion for education as a math instructor at Penn State University. He expanded his educational experience launching and running an Executive Education business - training over 100,000 students per year. As the CEO of Learner, Mike focuses on accelerating learning and unleashing the potential of students. 

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