Look around you, have you ever wondered that you are surrounded by geometrical shapes? The bangles your mother wears, the ring worn by your sister, the circular-shaped clock, the ring light used by teenagers to take good quality pictures. These are all examples of circles. We can define a circle as a unique type of ellipse which has an eccentricity value equal to 0. There are two foci that are coincident.

Radius is equal to the distance from the midpoint or the center of any given circle to the outer boundary of the circle. Let’s know what the diameter of any given circle means. Diameter is defined as the line that is responsible for dividing the circle into two equal parts. In this article, we are going to discuss the definition of circle as well as the diameter of circle.

**What is Circumference?**

The circle has been around for a long time. People used to assume that the moon, sun, as well as other planets, were round since there was no understanding of 3D shapes—mathematicians studied circles, which aided them to develop calculus and astronomy.

The circumference of a circle is equal to the perimeter of the given circle. It is the entire circumference of the circle. The circumference of a circle is equivalent to the product of the constant as well as the circle’s diameter. This measurement of a circle’s diameter is necessary for a human taking a stroll through a circular picnic area or for a circular table that needs to be bordered. The circumference of a circle is known to be a linear variable measured in the same measures as the length.

Circumference of circle = 3.14*d ———–(1) |

**Circle Formulas**

There are many formulas of a circle that you need to be aware of. The basic formulas you need to be aware of are – an area of any given circle, the perimeter of a circle, the circumference of circle, the diameter of any circle as well as radius of the circle.

**What is Diameter of a Circle?**

We have already discussed what the diameter of a circle is. The formula to calculate the diameter of any circle is 2r which means the diameter is twice the length of the radius.

Diameter Formula = 2*r , where r is equal to the radius of the circle —— (2) On substituting the value of d discussed above in the equation (1) we get, Circumference of the circle is equal to 3.14*2*r |

**Solved Examples**

**Example 1:** Find the circumference of a circle where the radius is equal to 10 cm.

**Solution:** Let’s note down the given information,

Radius = 10 cm

We already know the formula to calculate the circumference of a circle = 3.14*2*r

Putting the value of radius we get = 3.14*2*10 = 62.8 cm

Therefore, the circumference of the circle is equal to 62.8 cm.

**Example 2:** The circumference of a circular park equals 72.4 cm. What will be the diameter of the circular park?

**Solution:** Let’s note down the given information,

Circumference = 72.4 cm

We already know the formula to calculate the circumference of a circle = 3.14*2*r

Let’s try to find the radius of the circular park,

72.4 = 3.14*2*r

Radius of the circular park = 72.4/ (3.14*2) = 72.4/6.28

Therefore, the radius of the circular park is equal to 11.52 cm

If you want to know more about the diameter of circle as well as the circumference of a circle, do visit Cuemath!