Question

the ratio of circumference and area of the circle is 2:7 find its circumference​

Answer 1

Take ratio and then simply further solve it out

Answer 2

Answer:

Given :

The ratio of circumference and area of a circle is 2:7 .find its circumference.

To find :

Circumference of circle

Solution :

First of all we have to know formulas of circumference and area of circle :

${\boxed{\sf{ Circumference \ of \ circle \ = \ 2 \pi r }}}$

${\boxed{\sf{\ Area \ of \ circle \ = \ \pi r^2 }}}$

So according to question,

$\begin{gathered}\longrightarrow\sf 2\pi r : \pi r^2 = 2 : 7 \\\\\\ \longrightarrow\sf \dfrac{2 \pi r}{\pi r^2} = \dfrac{2}{7} \\\\\\ \longrightarrow\sf \dfrac{2}{r} = \dfrac{2}{7} \\\\\\ \longrightarrow\bold{2r = 14} \dots \dots (i)\end{gathered}$

⟶2r=14……(i)

Now circumference of circle,

$\begin{gathered}\longrightarrow\sf Circumference_{circle} = 2 \pi r \\\\\\ \longrightarrow\sf Circumference_{circle} = 2r \times \pi \\\\\\ \longrightarrow\sf Circumference_{circle} = 14 \times \pi \\\\\\ \longrightarrow\underline{\boxed{\bold{Circumference_{circle} = 14 \pi }}} \\\\\\\\ \therefore\underline{\sf{Circumference \ of \ circle \ = 14 \pi \ units ] }}\end{gathered}$