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Question
Find the area of a ring whose outer and inner radii are respectively 23 cm and 12 cm.
Solution
Let r1 cm and r2 cm be the radii of the outer and inner boundaries of the ring, respectively.
We have:
r1 = 23 cm
r2 = 12 cm
Now,
Area of the outer ring `= π"r"_1^2`
`=22/7xx23xx23`
= 1662.57 cm2
Area of the inner ring `= π"r"_2^2`
`= 22/7xx12xx122`
= 452.57 cm2
Area of the ring = Area of the outer ring - Area of the inner ring
= 1662.57 - 452.57
= 1210 cm2
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