Question

What is the circumference of a circle having area 38.5 sq. cm. ?

(0.5 Points)

a.22 cm

b.24 cm

c.11 cm

d.44 cm

​

Answer 1

Answer:

Area of a circle =πr

2

∴38.5=πr

2

∴

7

22

×r

2

=38.5

⇒r

2

=38.5×

22

7

⇒r

2

=12.25⇒r=

12.25

∴ r=3.5

Now, Circumference of circle =2πr

∴ Circumference of circle =2×

7

22

×

10

35

∴ Circumference of circle =22m

Answer 2

The circumference of the circle is 22 cm .

Option (a) is correct .

Step-by-step explanation:

Formula

$Area\ of\ a\ circle = \pi r^{2}=πr$

$Circumference\ of\ a\ circle = 2\pi r=2πr$

Where r is the radius of the circle .

As given

The area of a circle is 38.5 sq cm .

$\pi = 3.14π=$

$38.5=3.14\times r^{2}38.5=3.14×r²$

$r^{2} = \frac{38.5}{3.14}r 2 = 3.14 /38.5$

r² = 12.3

r = √12.3

r = 3.51 cm (Approx)

Thus

$Circumference\ of\ a\ circle = 2\times 3.51\times 3.14=2×3.51×3.14$

= 22 cm (Approx)

Therefore the circumference of the circle is 22 cm .

Option (b) is correct .

BE BRAINLY ⚡☃️