A circle is a locus of a point which moves at a fixed distance from the point around a fixed point. Anything in the form that’s round is a circle. The radius of the circle is the fixed distance from the centre.
Examples – Wheel, pizzas and so on.
- Radius – The circle radius is the line that connects the circle centre to the outer boundary. Typically it’s represented with r, or R. Radius plays an important role in the formulation for area and circumference of a circle.
- Diameter – The circle diameter is the line separating the ring into two equal parts. It’s just the double of the circle radius and is denoted by d or D.
Relationship between the radius and diameter of the circle
|Diameter = 2 ✕ Radius
D = 2 ✕ R or
D = 2 ✕ r
|Radius = Dimeter/2
R = D/2 or
R = d/2
Definition of the area of the circle
The area is the region in a two-dimensional plane which occupied the shape. The area occupied by a complete cycle of the circle radius on a two-dimensional plane is the area beyond that circle.
Formula to determine the area of the circle
Let us consider a circle with radius r
From the figure
r = radius from the centre of the circle O.
Then the area of the circle A is equal to the product of the pi and square of the radius.
A = πr2
Π = 22/7 or 3.14
r = radius.