Circumference calculation Explained

Understanding what a circumference of a circle is and also how to calculate it is vital as you move to higher level math. In this post you will discover the answers come the complying with questions.

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What is the one of a circle?How can you calculation the circumference of a circle?

What is the circumference of a circle?

The circumference the a circle is the distance around the external of the circle. The is favor the perimeter of other shapes choose squares. You deserve to think of it as the heat that specifies the shape. For forms made of right edges this line is called the perimeter however for one this specifying line is dubbed the circumference.

This diagram shows the circumference of a circle.


There are two other important ranges on a circle, the radius (r) and the diameter (d). The radius, the diameter, and the circumference space the 3 defining elements of every circle. Offered the radius or diameter and pi you deserve to calculate the circumference. The diameter is the distance from one side of the circle to the other at that widest points. The diameter will constantly pass through the center of the circle. The radius is half of this distance. You can also think that the radius as the distance between the facility of the circle and its edge.

This diagram reflects the circumference, diameter, center, and radius ~ above a circle.


How deserve to you calculation the circumference of a circle?

If you recognize the diameter or radius the a circle, you have the right to work out the circumference. To start with, remember that pi is an irrational number written with the price π. π is about equal to 3.14.

The formula for functioning out the one of a circle is:

Circumference of circle = π x Diameter the circle

This is generally written as C = πd. This tells united state that the one of the one is three “and a bit” times as long as the diameter. We can see this ~ above the graphic below:


You can likewise work the end the circumference of a one if you know its radius. Remember the the diameter is double the length of the radius. We currently know that C = πd. If r is the radius the the circle, climate d = 2r. So, C = 2πr.

Example 1

If a circle has actually a diameter the 10cm, what is the circumference?


We recognize that C = πd. Since the diameter is 10cm, we know that C = π x 10cm = 31.42cm (to 2 decimal places).


Example 2

If a circle has a radius that 3m, what is its circumference?


We understand that C = 2πr. Because the radius is 3m, we recognize that C = π x 6m = C= 18.84m (to 2 decimal places).

Example 3

Find the absent length (marked through a ?) ~ above the chart below:



The absent length is the circumference. Making use of the understanding that the diameter is 4.3m ~ above the diagram and knowing that C = πd, we deserve to calculate the circumference. Through a little thinking we can quickly figure out that, C = π x 4.3m = 13.51m (to 2 decimal places). The lacking length is 13.51m.

How to calculate the circumference of the Earth

Have you ever before wondered how large the planet is? Well, utilizing pi it’s possible to work-related out the one of the Earth! researchers have uncovered that the diameter the the earth is 12,742km. Given this information, what is the one of the Earth? obtain out a piece of document and a calculator and see if you have the right to work it out on her own.

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Again, we know that C = πd, and also that the diameter that the planet is 12,742km. Utilizing this details we deserve to calculate the circumference of the earth as C = π x 12,742km = 40,030km.

Formula for the Circumference and Area that a Circle

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