If the area of a circle is $154\ cm^2$, then find its circumference.

Given: Area of a circle is $154\ cm^2$.

To do: To find its circumference.

Solution:

Let $r$ be the radius of the circle.

Therefore, area of the circle$=\pi r^2$

$\Rightarrow \pi r^2=154$

$\Rightarrow \frac{22}{7}\times r^2=154$

$\Rightarrow r^2=\frac{154\times 7}{22}$

$\Rightarrow r^2=7\times 7$

$\Rightarrow r=\sqrt{7\times 7}$

$\Rightarrow r=7\ cm$

Therefore, circumference of circle$=2\pi r$

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

$=44\ cm$

Thus, the circumference of the circle is $44\ cm$.

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Updated on: 10-Oct-2022

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