# How to calculate the circumference of a circle

Although the circumference of a circle is proportional to the length of its boundary, it cannot be calculated using a ruler (scale) like other polygons. This is attributable to the fact that a circle is a curvy figure. As a result, we utilize a formula that uses the radius or diameter of the circle and the value of Pi () to calculate the circumference of a circle.

The
below equation explain the relationship between the circumference and the
radius of a circle

c=2πr

Where
is a constant and has a fixed value which is equal to 3.14159265..... The exact
figure is impossible to calculate. We generally use approximations like3.14 or
22/7 because it’s an irrational number.

Method
to calculate the circumference of a circle

**Method
1: Using
diameter to calculate the circumference of a circle:**

Use
the formula

C=π×d

If
we know the diameter we can determine the circumference. In this relation,
"C" symbolizes the circumference of a circle, and "d"
symbolizes its diameter. That is to say, we can find the circumference of a
circle just by multiplying the pi by diameter. Substituting the value the
numerical value is 3.14 or 22/7.plug the given value of the diameter into the circumference
formula and solve. For further practice examples problem below:

**Example****:** A circular bike wheel
with a diameter of 10 feet. Calculate the circumference of a circular bike
wheel.

To
calculate the circumference of the circular bike wheel. The diameter of thecircular
bike wheel is 10 feet. Now substituting the values in the formula

C=π

C=π×10

C=31.42feet

**Method
2: Using
radius to calculate the circumference of a circle:**

Use the formula

C=2πr

This
relation represents the radius of the circle.

A
radius is the length of the line segment from the center of the circle to its
other endpoint on the boundary of the circle.

This
formula is similar to C=π d. That's because the radius is half of its
diameter, so the diameter can be written as d=2r.

Substitute
the given radius value into the above relation and solve it. For further
practice examples problem below:

Problem: You are cutting out the
ribbon to wrap around the edge of the bangle. The radius of the bangle is 2
inches.

Solution: To calculate the circumference
that you need just, putting the values of radius in a given equation

C=2πr

C=2

C=12.57inches