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How To Calculate The Area Of Circle If Diameter Is Given?

A circle is a shape or plan region whose boundary is a bunch of straight lines equal in distance to each other at 360 degrees from a common point usually called as a center.

The circle has a great prominence in our daily life; for illustration imagine a world where there is no wheel or circle shape then there will be no transportation so we can say that without circle we can’t envisage our life being easy.

As the circle is used daily in our life, there is need to determine its area as it will help in designing of any object or if you want to store any circle shaped object, calculating area will help in this matter. To learn how to determine the area of circle read the full article.

Calculating Area of Circle using Radius

Usually, the formula of a circle is used in the promptitude of a radius. The span between the center and the boundary line is known as the radius and it is represented by “r”. If you are given the radius then the formula you will use is

Area = Pi * radius* radius

Radius of a circle

For further understanding, example is given below

area of the circle in the form of radius

Let’s say we have a circle whose radius is 3.5 cm. Now follow these steps.

Step 1

Take the square of radius or multiply the radius with itself.

3.5*3.5 = 12.25 cm2

Step 2

Multiply the answer with the value of pi which is 22/7 or approximately 3.14

12.25*3.14 = 38.465 cm2

So the area is near about 38.465 cm2

Calculating Area using Diameter

A line that divides the circle in half and it passes through the center is known as the diameter. We can also determine that is 2 times of radius and it is represented by “d”.

Diameter = 2* radius

diameter of circle

We can also calculate the area directly using diameter. Formula of area of circle in the form of diameter is

Area = pi * (diameter/2)*(diameter/2)

Area = (1/4)* pi * d2

area of circle in the form of diameter

For the sake of understanding, we will solve the previous example using the formula of a diameter.

As the radius is given as 3.5 cm. we can convert it into the diameter

Diameter = 2* radius

Diameter = 2 * 3.5

Diameter = 7 cm

Now we have the diameter 7 cm or it can be given to us directly in that case we don’t have to calculate it. Now follow these steps

Step 1

Take the square of diameter or multiply it by itself

7*7 = 49 cm2

Step 2

Multiply it by pi value

49*3.14 = 153.86 cm2

Step 3

Now multiply it by 1 and then divide by 4 or you can directly divide it by 4 as 1 is an identity element which gives the same number by which it is multiplied.

153.86/4 = 38.465 cm2

Area = 38.465 cm2

So from both examples given above, we concluded that area is same whether you use the formula in the form of radius or diameter. If you liked the post or have any suggestions then hit it down in the comments section.


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