# What is the circumference of the circle whose area is 25pi ?

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

The area of a circle is given as pi*r^2.

Here the area is 25*pi

pi*r^2 = 25*pi

=> r = sqrt 25

=> r = 5

Now the circumference of a circle is 2*pi*r = 2*pi*5 = 10*pi.

The required circumference is 10pi or 31.42 units.

hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted on

Given the area of the circle is 25pi.

But, we know that the formula of the area of a circle is given by:

A = r^2 * pi

We will substitute:

==> A = r^2 * pi = 25*pi

We will divide by pi.

==> r^2 = 25

==> r= 5

Then, the radius of the circle is r= 5.

Now we will calculate the circumference.

We know that:

C = 2*r*pi

==> C = 2* 5 * pi  = 10pi = 31.42 ( approx.)

Then, the circumference of the circle is 10pi = 31.42 units ( approx.)

neela | High School Teacher | (Level 3) Valedictorian

Posted on

Area of the circle = pr^2.

Given the area = 25pi.

=> pir^2 = 25pi.

=> r^2 = 25pi/pi = 25.

=> r = sqrt25 = 5.

Therefore the radius of the given circle = 5 units.

Therefore the circumference of the given circle = 2pir = 2pi* 5 = 10pi = 31.42 units approximately.