There are several two dimensional(2D) shapes in mathematics which we use in our daily life such as square, rectangle, triangle, circle, oval etc.

In this article, we will focus on the basics of the circle and its various topics.

There are several topics which we will cover in this article are-

1. What is Circle?

2. Radius of a circle

3. Diameter of circle

4. What is circumference(Perimeter) of a circle?

5. Arc of circle

6. Chord of circle

7. Tangent of circle

8. Secant of circle

9. Area of circle

10. Sector of a circle

11. Segment of a circle

Now cover all the topics step by step. Let's discuss circle definition?

# 1. What is a Circle?

The circle is a closed rounded shape (without corner) of constant radius.

- The boundary of the circle is at an equal distance from its centre.

## 2. Radius of Circle

Radius is a line segment which joins the centre of circle and boundary of a circle.

- Size of a circle depends on its radius if the radius is small then the size of the circle is small.

- If a radius is large then the circle is large.

## 3. Diameter of Circle

Diameter is a line segment which passes through the centre of the circle and joins the boundary of the circle from both ends.

Diameter is twice of radius(Diameter = 2×Radius)

- Diameter is always passed through the centre of the circle.

## 4. What is Circumference of Circle?

The circumference is the length of the circle's boundary.

- The circumference is also known as the perimeter of a circle.

## 5. Arc of Circle

Arc of a circle is a part of the whole circumference of the circle.

## 6. Chord of Circle

A chord is a line segment which divides the circle into parts. Its both ends touch the boundary of the circle.

- Diameter is the longest chord in any circle.

## 7. Tangent of Circle

Tangent is a line or line segment on which radius of the circle is perpendicular.

Or

Tangent is a line or line segment which touches the circle at any one point only.

## 8. Secant of Circle

Secant is a line or line segment which intersect the circle at any two points.

## 9. Area of Circle

Surface or region enclosed between the boundary of the circle is known as the area of circle.

Or

Surface enclosed inside the circumference of a circle is known as the area of a circle.

Area of circle formula = πr²

Where,

π = 22/7 or 3.14

r = radius of circle

## 10. Sector of Circle

The area enclosed between an arc and two radii is known as sector or sector of a circle.

Area of sector of circle formula = (πr²)×(θ/360°)

Where,

r = radius of circle

π = 22/7 or 3.14

θ = Angle of sector

### Minor sector

If the area of a sector is less in circle then it is known as a minor sector.

### Major sector

If the area of a sector is more in circle then it is known as a major sector.

## 11. Segment of Circle

The area enclosed between an arc and chord of a circle is known as a segment of a circle.

Area of segment of circle formula = r²{πθ/360° - sin(θ/2)×cos(θ/2)}

Where,

r = radius of circle

π = 22/7 or 3.14

θ = Angle of segment

### Minor segment

If the area of a segment is less in circle then it is known as a minor segment.

### Major segment

If the area of a segment is more in circle then it is known as a major segment.

## Question/Answer on Circle

### 1. How to find the area of circle?

Area of circle maybe finds by area formula. We will put values of radius of the circle and π in the below formula to get the area.

Area of Circle Formula = πr²

Where,

r = radius of circle

π = 22/7 or 3.14

Let's take an example-

#### Find the area of circle of radius 7 cm.

Given:- Radius(r) = 7cm

- Area of Circle = πr²
- πr²
- (22/7)×7²
- 22×7
- 154 cm²

### 2. What is circumference and area of circle?

#### Circumference of Circle

- Circumference of circle is a length of the circle's boundary.

- Circumference of circle formula is 2πr.

#### Area of Circle

- Area of circle is a region enclosed in circle's boundary.

- Area of circle formula is πr².

### 3. What is the name of a circle 3d shape?

The name of circle 3d shape is a sphere.

Example of Sphere - Football, Marble, etc.

### 4. Is circle 2d shape?

Yes, Circle is a 2d shape. Because the circle has not any thickness.

### 5. What is the exact circle definition?

Closed rounded shape(without corner) of constant radius is known as a circle.

### 6. Is the whole angle of circle 360 degrees?

Yes, circle makes the whole angle is 360 degree.

So, these are the basics of a circle.

Finally, we discussed several topics of a circle such as circle definition, circle area formula, circle 3d shape, area of sector of circle, area and circumference of circle, etc.

You may comment us on any query related to this article.