Question

What is the circumference of a circle with an area of 20 pi

Answer 1

28.1 units

Explanation:

Area of circle= πr², where r is the radius.

Given that the area is 20π,

20π= πr²

Divide both sides by π:

20= r²

Square root both sides:

`r = √(20)`

`r = √(4(5))`

`r = ( √(4) )( √(5) )`

`r = 2 √(5)`

Circumference of circle= 2πr

Substitute the value of r:

Circumference of the circle

`= 2(\pi)( 2√(5) )`

`= 4\pi √(5)`

= 28.1 units (3 s.f.)