We all have studied the concept of circles. Do you know what the circumference of the circle is? The circumference of the circle is nothing but the boundary of the circle. How can you measure the circumference of the circle?

If you cut open a circle and straighten it, the line that measures is the circumference of the circle.

**Structure of a Circle in Relation to the Circumference of the Circle**

A circle has many structural elements. A circle can have a center, radius, and diameter. How are these radii and center related to the circumference?

Center – The center of the circle can be defined as the point which is equal distance from the center and thus forms the circumference of the circle.

Radius – The radius of the circle is the measurement from the center to the circumference.

Diameter – The diameter of the circle is the maximum distance between any two points which is located on the circumference of the circle.

**What is the Formula for Circumference of the Circle?**

The circumference of the circle is the measure of the boundary of the circle. This circumference of the circle is measured in the units of lengths like meter, centimeter, etc. The formula which we can apply in the calculation of the circumference of the circle is as follows:

**Circumference = 2πR**

In this formula, R represents the radius of the circle, π (pi) is the constant value. Here the value of π = 3.1415926535897…

**What is Pi? **

Pi or the symbol π is a Greek-lettered word. This is considered an important constant in the study of mathematics. The pi value represents the ratio of the circumference of the circle and the diameter of the circle. Or this can be represented as the ratio of circumference to twice the measurement of radius.

This ratio is constant irrespective of the measurement of the circumference of the circle and the radius of the circle. The ratio is equal to pi.

The value of pi is 3.1415926535897… which is an infinite number, and thus this will make the calculation impossible. Thus for the purpose of easy calculation, we use pi or π = 22/7. We can also take approximate the value to 3.14 and do the required calculation. To simplify even further, we can take the value as 3 too.

Example: Estimate the circumference of a circle if the radius of the circle is 16 cm. (estimating π = 22/7)

Answer: R or radius (which is given) = 16 cm

Circumference of the Circle = 2πR

= 2 * 22/7 * 16

= 100.57 cm

**Other Facts of the Circle**

Let us know some other interesting facts about the circle:

**1. Do you know what is meant by the area of the circle?**

Well, the area of the circle is the area that is encompassed by the circle. The formula to find out or calculate the area of the circle is A = πr2.

Here r is the radius of the circle while A represents the area of the circle. This formula of the area of the circle can be applied to any circle even with different measurements of radii.

**2. What is the perimeter of the Circle?**

Just like the area, there is a perimeter of the circle also. The perimeter of the circle is the distance that is covered by the boundary of the circle. The formula for perimeter is C = 2πr

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