We’ve all seen circles in our lives. They have a perfectly round shape, making them ideal for hula-hooping! This article will define a circle, as well as its properties and parts. Look around, you’ll find circles all around you, the bangles your mom wears, the clock hanging on the wall, the lemon you eat! The circle has a long history. Since there was no concept of 3D shapes, people used to believe that the moon, sun, and other planets were circular—mathematicians studied circles, perimeter of circle**, **and other properties of circles, which helped them develop calculus and astronomy.

**What is a Circle in Geometry?**

The term “circle” comes from the Greek word for “hoop” or “ring.” It’s a two-dimensional figure which is in a round plane and whose boundary, also known as circumference, has all points equidistant from the centre.

Let’s first discuss what the diameter of a circle is!

A circle’s diameter is defined as any straight line segment that passes through the centre of the circle; it has endpoints on the circumference. Did you know the diameter is known to be the longest chord of a circle. In engineering, this symbol Φ is used to represent diameter. This symbol appears frequently in technical specifications and drawings. A Φ25 mm indicates that the circle’s diameter is 25 mm.

**Invention of Circle**

There’s no way of knowing for sure, but anthropologists generally agree that the circle existed long before history was written down. The Egyptians were also thought to be the inventors of geometry by the Greeks. Now, let’s take a look at what a circle is. According to Euclid, the geometric figure circles are “a plane figure bounded by one curved line, and such that all straight lines drawn from a certain point within it to the bounding line are equal.” The circumference of the bounding line is known as its centre, and the point is known as its centre.”

Also Read: Venn Diagrams Revolutionised Visualisation

**What is the Perimeter of a Circle?**.

As we have already discussed, any shape’s perimeter is defined as the total distance around the shape. Perimeter of any figure denotes the length of any shape that can be expanded linearly. Depending on the dimensions, the perimeters of different figures can be equal in size.

Formula of Perimeter of Circle = 2.π.r

To find the perimeter of a circle, use the perimeter of a circle formula.

Example: If there’s a circle with a radius of 6 cm, then the circumference of the circle will be, Circumference = 2πr = 2 x 3.14 x 6 = 37.68 cm

The circumference of a circle is the term used to describe its perimeter. As a result of the perimeter of a circle informing us about the circumference of a circle, it is also known as the circumference of a circle formula.

**Facts About Circles**

- Circles have a high level of symmetry.
- All shapes with the same area have the shortest perimeter, which is a circle.
- The circle shape is popular among humans and can be found in a variety of designs.
- One of the most significant inventions in human history was the wheel (a circle shape).
- Circles and spheres are also common in nature; can you think of any examples?
- A circle is a two-dimensional round shape that resembles the letter ‘O.’
- In mathematics, a circle denotes the shape’s boundary, whereas a disc denotes the entire shape, including the inside.
- The radius is defined as a straight line drawn from the centre of a circle to its edge.
- We have already discussed that the diameter is defined as a straight line that passes through the centre of a circle from one side to the other.
- All points on the edge of a circle are the same distance to the centre of the circle.

To learn more about circles in a fun way (Hybrid Learning), you can visit cuemath.com.