Question

Find circumference of circle whose area is 1386cm

Answer 1

Given:-

• The area of a circle is 1386cm².

To find:-

• Find the circumference of the circle ?

Solutions:-

• Let the radius of the circle be 'r' cm

We know,

The area of the circle = πr²

According to the question:-

=> 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

According to question:-

=> 2 × 22/7 × 21

=> 44 × 21/7

=> 44 × 3

=> 132

Hence, the circumference of circle is 132 cm².

Some Important:-

• Diameter of a Circle D = 2 × r
• Circumference of a Circle C = 2 × π × r
• Area of a Circle A = π × r2

Where,

• r denotes the radius of the circle.
• d indicates the diameter of the circle.
• c indicates circumference of the circle.