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Area of a Circle

A circle is defined as a closed curve. It is said to be the path of a point moving at a constant distance from a particular fixed point. This distance is called radius and this point is known as center of the circle.
Circle Radius
Here, we shall discuss about area of circle.
Circle is a two-dimensional figure. Area of a circular object is defined as the measurement of space occupied by it.

Related Calculators
Area Calculator Circle
 

Units of Area of Circle

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Area is measured in square unit or unit square or $(unit)^{2}$.

For example, square meter or $m^{2}$, square centimeter or $cm^{2}$. The smaller measurement of area can be square milimeter or $mm^{2}$ and larger measurement of area can be are and hectare.

Formula Related to Area of Circle

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The
formula for calculating area is given below:
A = $\pi r^{2}$

Where, $A$ = Area of circle and $r$ = Radius

We know that radius is half the diameter. If d denotes diameter of the circle, then we have $r$ = $\frac{d}{2}$

Substituting this value in the above formula of area, we get

A = $\pi$ $(\frac{d}{2})^{2}$

A = $\frac{\pi d^{2}}{4}$
One can even find radius of circle when its area is given, by performing little transformation in the formula of area:
r = $\sqrt{\frac{A}{\pi}}$

Example:

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1)  Find the area of circle with radius equal to 6.5 inch using $\pi$ = 3.14.


Solution:
Formula for area 
of circle is,

A = $\pi r^{2}$


Substitute the values of radius and $\pi$, we get


A = $3.14 \times (6.5)^{2}$


= 3.14 $\times$ 42.25

=
132.67 square inch.

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