Question

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

2 points

14 pi

7/pi

7pi

14/pi

​

Answer 1

Answer:

14/pi

Step-by-step explanation:

please follow and mark as brainliest

Answer 2

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 :

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

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

So according to question,

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

Now circumference of circle,

$\longrightarrow\sf Circumference_{circle} = 2 \pi r \\\\\\ \longrightarrow\sf Circumference_{circle} = 2r \times \pi \\\\\\ \longrightarrow\sf Circumference_{circle} = 14 \times \pi \\\\\\ \longrightarrow\underline{\boxed{\bold{Circumference_{circle} = 14 \pi }}} \\\\\\\\ \therefore\underline{\sf{Circumference \ of \ circle \ = 14 \pi \ units \ \ [Option (i)] }}$