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.

Answer 1

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