Question

The area of a circular disc is 38.5 cm2 . Find it circumference .

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Answer 1

Answer:

Area of circle=πr^2

Circumference of circle=2πr

Step-by-step explanation:

Area of circle=πr^2

38.5=22/7×r^2

38.5×7/22=r^2

269.5/22=r^2

12.25=r^2

r=3.5

Circumference of circle=2πr

=2×22/7×3.5

=2×22×0.5

=44×0.5

=22cm

Hope it helps!!

Answer 2

Given :

⬤ Area of Circular Disc is 38.5 cm².

To Find :

⬤ Circumference of Circle .

Formula Used :

$\bf[\:{Area \: of \: Circle = \pi{r}^{2}}\:]$

Solution :

First , We have to Calculate Radius of the Circular Disc . Hence ,

38.5 = πr²

$:\implies\sf{38.5 = \dfrac{22}{7} \times{r}^{2}}$

$:\implies\sf{38.5 \times{7} = 22{r}^{2}}$

$:\implies\sf{269.5 = 22{r}^{2}}$

$:\implies\sf{\dfrac{269.5}{22} = {r}^{2}}$

$:\implies\sf{12.25 = {r}^{2}}$

$:\implies\sf{\sqrt{12.25} = r}$

$:\implies\sf{3.5 = r}$

Therefore , Radius is 3.5 cm .

Formula Used :

$\bf[\;{Circumference \: of \: Circle = 2\pi{r}\:]}$

Now :

2πr

$:\implies\sf{2 \times\dfrac{22}{7} \times{3.5}}$

$:\implies\sf{2 \times\dfrac{22}{7} \times\dfrac{35}{10}}$

$:\implies\sf{\dfrac{44}{2}}$

$:\implies\sf\bf{22}$

Therefore , Circumference of Circle is 22 cm .