Another term of Perimeter of a circle is known as circumference of a circle. This page is going to guide you how to find the perimeter of a circle.

**Formula :**

**Circumference of circle = 2
Π r**

Here the value of Π is either 22/7 or 3.14 and "r" stands for radius of a circle.

Here the length of the red line is known as circumference of a circle. Now let us see some example problems to understand this topic better.

**Example 1:**

Find the circumference of a circle whose radius is 14 cm.

**Solution:**

To find the circumference of circle we need to use the formula to find the circumference of circle.

Circumference of circle = 2 Πr

= 2 **⋅** (22/7) **⋅** 14

= 2 **⋅** 22 **⋅** 2

= 4 **⋅ **22

= 8 cm

**Example 2:**

Find the diameter of circle whose circumference is 42 cm.

**Solution:**

Circumference of circle = 42 cm

2 Π r = 42

2 **⋅** (22/7) **⋅** r = 42

r = (42 **⋅** 7) / (2 **⋅** 22)

r = 294/44

r = 6.68 cm

Now we have to find the diameter for that we have to multiply the radius by 2.

Diameter = 2 r

= 2(6.68)

= 13.36 cm

**Example 3:**

A moon is about 384000 km away from the earth and its path around the earth is nearly circular. Find the distance traveled by moon every month.

**Solution :**

In one month, the moon describes a full circle about the earth.

Now the circumference = 2 Π r

= 2 **⋅** (22/7) **⋅ **384000 km

= 2413714 km

Hence the distance traveled by the moon = 2413714 km

**Example 4 :**

A copper wire is in the form of a circle with radius 35 cm. It is bent into a square. Determine the side of the square.

**Solution :**

Given: Radius of a circle, r = 35 cm.

Since the same wire is bent into the form of a square,

Perimeter of the circle = Perimeter of the square

Perimeter of the circle = 2Πr units

= 2 **⋅ **(22/7) **⋅ **35

P = 220 cm

Let ‘a’ be the side of a square.

Perimeter of a square = 4a units

4a = 220

a = 55 cm

Side of the square = 55 cm.

After having gone through the stuff above, we hope that the students would have understood circumference of a circle.

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