November 10, 2008

This resource has been contributed by Winpossible, and can also be accessed on their website by clicking here - Circumference of a Circle.

In this section, we will focus on the basics about a circle, radius, and circumference. You'll also learn the mathematical term pi and formula for the circumference of circles. A circle is a shape with all the points at same distance from the center and the distance around a circle is called the circumference. The distance across a circle through the center is called the diameter. The radius of a circle is the distance from the center of a circle to any point on the circle. The diameter of a circle is twice as long as the radius and this relationship is expressed in the formula:

*d* = 2*r*

where*d* is the diameter and *r* is the radius.

If points*A*, *B*, and *C* are on the circle with center *O*, then

*OA* = *OB* = *OC* = *r*

to find circumference, we multiply pi (?) and the diameter of the circle i.e.

* C* = ?*d*

Given the circumference of a circle 220 cm, you can work out the diameter, which comes to 70 cm. You can also find the circumference of a circle, when the radius is given by*r*. The formula for finding circumference is:

*C* = 2?*r*

For example, if the radius of a circle is 3.5 units, then circumference of a circle is 7? units.

In this section, we will focus on the basics about a circle, radius, and circumference. You'll also learn the mathematical term pi and formula for the circumference of circles. A circle is a shape with all the points at same distance from the center and the distance around a circle is called the circumference. The distance across a circle through the center is called the diameter. The radius of a circle is the distance from the center of a circle to any point on the circle. The diameter of a circle is twice as long as the radius and this relationship is expressed in the formula:

where

If points

to find circumference, we multiply pi (?) and the diameter of the circle i.e.

Given the circumference of a circle 220 cm, you can work out the diameter, which comes to 70 cm. You can also find the circumference of a circle, when the radius is given by

For example, if the radius of a circle is 3.5 units, then circumference of a circle is 7? units.

This FREE mini-lesson is a part of Winpossible's online course that covers all topics within Geometry. Click on the video below to go through it. If you like it, you can buy our online course in Geometry by clicking here.

- Mathematics > General
- Mathematics > Geometry
- Education > General

- Grade 9
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