# Circle Definition

In Mathematics, geometry is a branch that deals with the study of different shapes and their measurements. Basically, geometry is classified into two-dimensional geometry and three-dimensional geometry. Two-dimensional geometry deals with 2D shapes. It has only two measures, such as length and height. Circle, square, rectangle, etc., are examples of 2D shapes. Three-dimensional geometry deals with 3D shapes. It has length, height, and width. Cylinder, sphere, cube, cuboid are examples of 3D shapes. Here, let us discuss the circle definition, with its area and circumference/perimeter formula.

## Circle Definition in Maths

A circle is a two-dimensional figure, which is round in shape where all the points on the surface of the circle are equidistant from the centre point is called “P”. The distance from point P to the surface of the circle is called the radius of the circle (R). It has no edges or corners. Similarly, the semicircle is half of the circle and also a quarter circle is formed by splitting the circle into four equal parts.

## Circle Formula

Since a circle is a two-dimensional figure, it has an area and the perimeter. Let us discuss the formula for area and the circumference of a circle.

Area of Circle:

The area of the circle is the space occupied by the shape circle. The formula to calculate the area is given by

Area of Circle, A = πr2 Square units

Circumference of Circle:

Circle circumference is the enclosing boundary of any curved geometrical shape. The formula for the circumference of a circle is given by:

Circumference/ Perimeter of Circle = 2πr units

### Circle Example

Question:

Find the area and the circumference of a circle where the radius is 7 cm.

Solution:

Given: Radius, r = 7 cm

Now substitute the radius value in the formulas.

Area of Circle, A = πr2 Square units

A = (22/7)× 7× 7

A = 22 × 7

A = 154 cm2

Circumference of Circle = 2πr units

C = 2× (22/7) × 7

C = 2 × 22

C = 44 cm

Therefore, the area and the circumference of the circle are 154 cm2 and 44 cm, when the radius is 7 cm.

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