Area of circle

Let us study about area of circle,
The distance around a circle is called its circumference. The distance across a circle through its center is called its diameter. We use the Greek letter π (pronounced Pi) to represent the ratio of the circumference of a circle to the diameter. In the last lesson, we learned that the formula for circumference of a circle is: C = πd. For simplicity, we use π = 3.14. We know from the last lesson that the diameter of a circle is twice as long as the radius. This relationship is expressed in the following formula: d = 2r

The area of a circle is the number of square units inside that circle. If each square in the circle to the left has an area of 1 cm², you could count the total number of squares to get the area of this circle. Thus, if there were a total of 28.26 squares, the area of this circle would be 28.26 cm² However, it is easier to use one of the following formulas:


if the radius of this circle is r, the area, A of the circle will be:
A = πr²
a circle with the radius r

where π is a constant that is approximately equals to 3.14.


I hope the above explanation was useful.