# Find the circumference of a circular disk whose area is 100pi square centimeters.

### Find the circumference of a circular disk whose area is 100pi square centimeters.

The area of circle is given by the formula:

A = pi * r ^2

Substitute the given value of A into the formula, we get:

100 pi = pi * r^2

Divide...

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### Find the circumference of a circular disk whose area is 100pi square centimeters.

The area of circle is given by the formula:

A = pi * r ^2

Substitute the given value of A into the formula, we get:

100 pi = pi * r^2

Divide by pi on both sides:

100 = r^2

10^2 = r^2

It follows that

r=10

Circumference of circle is given by the formula C=2*pi*r

C = 2 * pi * 10

20*pi

The required answer: circumference of the disk is 20*pi cm

Approved by eNotes Editorial Team

Given that the area of the circle is A = 100pi cm^2.

We know that the area of the circle IS :

A = r^2 * pi = 100*pi

==> Divide by pi:

==> r^2 = 100

==> r= 10

Now we will find the circumference:

==> C = 2*pi *r

==> C = 2*pi* 10 = 20*pi

==> Then the circumference of the circle is = 20*pi

The area = 20*pi

We know that the formula for the area of a circle is:

A = r^2 *pi where r is the radius:

==> r^2 * pi = 100*pi

Now we will divide by pi:

==> r^2 = 100

==> r= 10

Now we will calculate the circumference:

We know that:

C = 2*pi*r

==> C= 2*10* pi

= 20*pi

Also we could write pi = 22/7

==> C = 20*22/7 = 62.89 cm

Approved by eNotes Editorial Team