Question

Find circumference of circle whose area is 1386cm

Answer 1

Given:

The area of a circle is 1386cm².

Find:

The circumference of the circle

Solution:

Let the radius of the circle be 'r' cm

We know,

The area of the circle = πr²

=> 1386 = 22/7 × r²

=> 1386 × 7 = 22 × r²

=> 9702 = 22 × r²

=> 9702/22 = r²

=> 441 = r²

=> √411 = r

=> 21 = r

=> r = 21cm.

Now,

The circumference of the circle = 2πr

=> 2 × 22/7 × 21

=> 44 × 21/7

=> 44 × 3

=> 132

Hence, the circumference of circle is 132 cm².

I hope it will help you.

Regards.

Answer 2

Answer:

Area of a circle of radius r =πr2 =1386cm2

22/7×r2 =1386cm2

r2=441cm2

r=21cm

Circumference of a circle of radius r =2πr

Circumference of circle of radius 21cm=2× 22/7×21=132cm

Hope this is helpful for you.