Question

calculate the area of a circular ring,whose internal and external radii are 3 cm and 1 cm respectively.

Answer 1

Internal radius given = 1 cm ( here we will use r for internal radii and R for external radii)

External radius given = 3 cm

=> Area of circular ring = π r^2
=> In order to evaluate or calculate the area of external and internal radius area

=> Therefore internal radii = 1 cm
=> formula to implemented = π r^2
=> ( π = 3.14 ) x 1^2 ( radii )
=> 3.14 x 1 x 1
=> 3.14 cm^2

Since 1 is a radii than a diameter so we can add 3 ( radii ) to 1 which will be 4

So external radii + internal radii = 4 ( we found the sum because in order to calculate area the circle will have radius, if in diameter we convert it into radius so to calculate area )

=> π R ^2
=> 3.14 x 4^2
=> 3.14 x 4 x 4
=> 50.24 cm ^2

So if we calculate by finding the sum of internal radii ( 3.14 cm^2 ) and external radii ( 50.24 cm^2 )

So their sum will be 50.24 + 3.14 = 53.58 cm^2

So area of circular ring is 53.58 cm^2

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