Find the radius of a circle whose circumference is
(a) $ 22 \mathrm{~cm} $
(b) $ 17.6 \mathrm{~cm} $
(c) $ 30.8 \mathrm{~cm} $
Take $ \pi=\frac{22}{7} $ in each case.

Given:

The circumference of a circle is:

(a) \( 22 \mathrm{~cm} \)
(b) \( 17.6 \mathrm{~cm} \)
(c) \( 30.8 \mathrm{~cm} \)

To do:

We have to find the radii of the circles.

Solution:

(a) Let the radius of the circle be $r$.

This implies,

$2 \pi r=22\ cm$

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

$r=\frac{7\times22}{44}$

$r=\frac{7}{2}\ cm$

The radius of the circle is $3.5\ cm$.

(b) Let the radius of the circle be $r$.

This implies,

$2 \pi r=17.6\ cm$

$2\times\frac{22}{7}\times r=17.6$

$r=\frac{7\times17.6}{44}$

$r=7\times0.4\ cm$

$r=2.8\ cm$

The radius of the circle is $2.8\ cm$.

(c) Let the radius of the circle be $r$.

This implies,

$2 \pi r=30.8\ cm$

$2\times\frac{22}{7}\times r=30.8$

$r=\frac{7\times30.8}{44}$

$r=7\times0.7\ cm$

$r=4.9\ cm$

The radius of the circle is $4.9\ cm$.

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Updated on: 10-Oct-2022

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