AREA OF A CIRCLE
The page area of a circle will teach you how to find the area of any circle. This page contains formulas, example problems and also practice questions to understand this topic in a better way.
Area:
Area of the circle means surface occupied by the figure.
In the above shape the part filled with red color is called area of a circle.
Formula :
Area = Π r ²
Here the value of Π is either 22/7 or 3.14 and r is known as the radius of a circle. Now let us see some example problems.
Example 1:
Find the area of the circle which is having the radius 21 cm.
Solution:
In this problem we need to find the area of the circle having a radius 21 cm. We need to apply this value instead of r in the formula.
Area of circle = Π r ²
= ( 22/7 ) x ( 21 )²
= (22/7) x 21 x 21
= 22 x 3 x 21
= 66 x 21
= 1386 cm²
Therefore the area of the given circle is 1386 cm²
Example 2:
Find the area of the circle which is having the diameter 28 cm.
Solution:
To find the area first we need to find the radius of the circle from the diameter.
Diameter = 28 cm
Radius = diameter/2
= 28/2
= 14 cm
Area of circle = Π r ²
= ( 22/7 ) x (14)²
= ( 22/7 ) x 14 x 14
= 22 x 2 x 14
= 44 x 14
= 616 cm²
Example 3:
The area of a circular region is 616 cm². Then find its diameter.
Solution:
Area of circle = 616 cm²
Π r ² = 616 cm²
(22/7) x r² = 616
r² = (616 x 7) /22
r² = (616 x 7) /22
r² = 28 x 7
r² = √(2 x 2 x 7 x 7)
r = 2 x 7
r = 14 cm
Diameter = 2 x radius
= 2 x 14
= 28 cm
Therefore diameter of the given circle is 28 cm.
Example 4:
Find the length of the rope by which a cow must be tethered in order that it may be able to graze an area of 9856 sq.meters
Solution:
In this problem we need to find the area of the circle having a radius 21 cm. We need to apply this value instead of r in the formula.
Area of circle = Π r ²
= ( 22/7 ) x ( 21 )²
= (22/7) x 21 x 21
= 22 x 3 x 21
= 66 x 21
= 1386 cm²
Therefore the area of the given circle is 1386 cm²
Related Topics
- perimeter of sector
- Length of arc
- Practice questions on length of arc
- Perimeter of square
- Perimeter of parallelogram
- Perimeter of rectangle
- Perimeter of triangle
- Area of a circle
- Area of Semicircle
- Area of Quadrant
- Area of sector
- Area of triangle
- Area of equilateral triangle
- Area of scalene triangle
- Area of square
- Area of rectangle
- Area of parallelogram
- Area of rhombus
- Area of trapezium
- Area of quadrilateral
- Area around circle
- Area of pathways
- Area of combined shapes
