What is the diameter of a circle if its area is 36π?

Answer 1

First of all remember the two circular equations.

A = pi r^2

C = 2 pi r or C = pi d ; there fore 2r = d

Using the first eq'n

A = pi r^(2)

Then

r^(2) = A / pi

r = sqrt[A/pi] (The radius)

Substituting

r = sqrt( 36 pi/ pi )

Cancel down by 'pi'

r = sqrt(36)

r = 6

From the 2nd eq'n 2r = d

So 2(6) = 12 The diameter.

Answer 2

We'll have to work backwards for this problem. Let's start with the area. The formula for the area of a circle is πr2. So to find the radius, our equation is now πr2=36π. We can divide both sides by π, so it becomes r2=36. Now we square root both sides, and it becomes r=6.

The diameter is twice the radius, so we multiply 6 by 2, and we find the answer. The diameter is 12.