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Question
A dinner plate is in the form of circle. A circular region encloses a beautiful design as shown in the following figure. The inner circumference is 352 mm and outer is 396 mm. Find the width of circular design.
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Solution
Let the radius of inner and outer circle be r and R, respectively.
Given, inner circumference = 352 mm
⇒ 2πr = 352 ...[∵ Circumference = 2πr]
⇒ `2 xx 22/7 xx r = 352`
⇒ `r = (352 xx 7)/(2 xx 22) = 2464/44` = 56 mm
And outer circumference = 396 mm ...[Given]
⇒ 2πr = 396
⇒ `2 xx 22/7 xx R = 396`
⇒ R = `(396 xx 7)/(2 xx 22)` = 63 mm
∴ Width of circular design = R – r = 63 – 56 = 7 mm
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