## Circumference calculation Explained

Understanding what a circumference of a circle is and how to calculate it is vital as you relocate to higher level math. In this article you will find out the answers come the complying with questions.

You are watching: What is the circumference of a circle if the radius is 4

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

## What is the one of a circle?

The circumference the a one is the distance roughly the outside of the circle. The is prefer the perimeter of various other shapes choose squares. You have the right to think the it as the line that specifies the shape. For forms made of straight edges this line is referred to as the perimeter yet for one this defining line is dubbed the circumference.

This diagram shows the one of a circle. There space two other important ranges on a circle, the radius (r) and the diameter (d). The radius, the diameter, and also the circumference space the 3 defining aspects of every circle. Offered the radius or diameter and also pi you can calculate the circumference. The diameter is the street from one next of the circle to the other at the widest points. The diameter will constantly pass v the facility of the circle. The radius is fifty percent of this distance. Friend can likewise think the the radius together the distance between the center of the circle and its edge.

This diagram mirrors the circumference, diameter, center, and also radius ~ above a circle. ## How can you calculate the one of a circle?

If you recognize the diameter or radius of a circle, you can work out the circumference. To begin with, remember the pi is an irrational number written through the price π. π is approximately equal to 3.14.

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

Circumference of one = π x Diameter the circle

This is commonly written together C = πd. This tells us that the one of the circle is three “and a bit” times as long as the diameter. We deserve to see this ~ above the graphics below: You can likewise work the end the one of a circle if you understand its radius. Remember that the diameter is dual the size of the radius. We already know the C = πd. If r is the radius of the circle, climate d = 2r. So, C = 2πr.

### Example 1

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

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

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

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

### Example 3

Find the missing length (marked through a ?) on the chart below: The absent length is the circumference. Using the knowledge that the diameter is 4.3m ~ above the diagram and also knowing that C = πd, we deserve to calculate the circumference. Through a little thinking us can easily figure the end that, C = π x 4.3m = 13.51m (to 2 decimal places). The absent length is 13.51m.

## How to calculate the circumference of the Earth

Have you ever wondered how huge the earth is? Well, making use of pi it’s feasible to occupational out the circumference of the Earth! researchers have discovered that the diameter the the earth is 12,742km. Offered this information, what is the circumference of the Earth? obtain out a item of file and a calculator and see if you deserve to work it out on your own.