Q129 of 131 Page 226

A dinner plate is in the form of a circle. A circular region encloses a beautiful design as shown in Fig. 9.70. The inner circumference is 352 mm and outer is 396 mm. Find the width of circular design.

Let the radius of inner and outer circle be r and R, respectively.


Given, inner circumference = 352 mm


⇒ 2∏r = 352


⇒ 2 × × r = 352


⇒ r = = 56 mm


and outer circumference = 396 mm


⇒ 2∏R = 396


⇒ 2 × × R = 396


⇒ r = = 63 mm


∴ Width of circular design = R – r = 63 -56 = 7 mm


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