Question

Find the circumference of the inner and the outer circles, shown in the adjoining figure. (Take π=3.14)

Answer 1

Hint: Here we go through by applying the formula of circumference of a circle i.e. $2\pi r$ because the radius is given in the question’s figure. For inner circumference use inner radius and for outer circumference use outer radius.

Complete step-by-step answer:
Here in the question it is given that
Radius of outer circle(R) =19 m.
$\therefore $ Circumference of outer circle $ = 2\pi R = 2 \times 3.14 \times 19 = 119.32m$
Now radius of inner circle(r) =19−10=9m because distance between the circumference of inner circle to outer circle is 10 m so we subtract it from the radius of outer circle to find the radius of inner circle.
$\therefore $Circumference of inner circle$ = 2\pi r = 2 \times 3.14 \times 9 = 56.52m$
Therefore the circumferences of inner and outer circles are 56.52m and 119.32m respectively.

Note: Whenever we face such a type of question the key concept for solving the question is, first find out the inner radius and outer radius of the circle by the help of the diagram given in the question then apply the formula of circumference of the circle to find out the required answer.