Question

Question 129

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

Answer 1

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

Given, inner circumference = 352 mm

$\Rightarrow 2\pi r=352$ [$\because$ circumference = 2 $\pi$ r]

$\Rightarrow 2\times \frac{22}{7}\times r=352$

$\Rightarrow r=\frac{352\times 7}{2\times 22}=\frac{2464}{44}=56mm$

and outer circumference = 396 mm

$\Rightarrow 2\pi R=396$

$\Rightarrow 2\times \frac{22}{7}\times R=396$

$\Rightarrow R=\frac{396\times 7}{2\times 22}=63mm$

$\therefore$ Width of circular design = R - r = 63 - 56 = 7 mm