Question

find the area of a circle whose circumference is 22cm

Answer 1

Solution :-

Given - Circumference of circle = 22 cm

Let the radius of the given circle be 'r'

Circumference of a circle = 2πr

⇒ 22 = 2 × 22/7 × r

⇒ r = (22 × 7)/(22 × 2)

⇒ r = 154/44

⇒ r = 3.5 cm

Area of circle = πr²

⇒ 22/7 × 3.5 × 3.5

⇒ 269.5/7

= 38.5 cm²

So, the area of the given circle is 38.5 cm²

Answer.

Answer 2

Given that, the circumference of a circle = C = 22 cm
We have to find the area of the circle.
i-e. A = ?
Solution:
The area of the circle is given by the formula as:
A = π r²   .............. (1)
where r is the radius of the circle.
Here, radius is known so first we calculate the radius of the circle.
Since, 
Circumference of a circle = 2 π r
r = Circumference of a circle / 2 π
r = 22 / (2) (3.14)
r = 22 / 6.28
r = 3.5 cm
Now put this value in equation (1), we get:
A = π r²
A = (3.14) (3.5)²
A = (3.14) (12.25)
A = 38.47 cm²
Which shows that area of a circle is 38.47 cm²
It is the required answer..