How to find Area of Circle

              To find an area of a circle, we have to know either the radius of the circle or

the diameter of the circle. From the diameter of the circle, we can calculate the radius through the formula 

   

                                          d = 2 x r

                        i.e. the radius of the circle is half of the diameter of the circle.

Now the formula for the area of the rectangle is 

                           Area of circle =  π × r²

where ,

                    π is a constant and represent 3.14 or we can use 22/7

           r²  is a the square of radius of circle or multiply the radius twice.

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Example 1 :

Finding the radius of a circle with radius 7 cm.

Using the formula listed above the radius of the circle is = π × r²

here,

 r²    = 7 x 7 = 49

π  = 3.14

therefore, area = 49 x 3.14 = 153.86 Square cm or cm^2.

^{Don't forget to add the unit square cm as area is always accompanied by the Square unit.} 

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Example 2 

Finding area of a circle whose diameter is given as 18 m.

First calculate the radius of the circle that is half of the diameter.

i.e. radius = d/2 =  18/2    = 9 m

Now area of the circle is = π × r²

we have,

 r² = 9 x 9 = 81 

π  = 3.14

Putting in the values in the formula to get the area of circle as = 3.14 x 81 = 254.34 sq. m