Question

If the area of a circle is 36pi, what is the circumference

Answer 1

Answer: 37.68

Step-by-step explanation:

First off our formulas are:

$Area: A=\pi r^2\\Circumference: C=2\pi r$

Solve for r in the area formula.

$A=\pi r^2\\r^2=\frac{A}{\pi} \\r=\sqrt[]{\frac{A}{\pi} }$

$r=\sqrt[]{\frac{36\pi}{\pi} }$

$r=\sqrt[]{36}$

r=6

Plug this into the circumference formula.

$C=2\pi r\\C=2(3.14)(6)\\C=37.68$

Answer 2

Answer:

113.1cm^2

Step-by-step explanation:

We know the area for a circle is pi * r^2, where r is the radius. We know the diameter, so all we need to do to find the radius is half the distance of the diameter, which would then be 6 cm. We plug in 6 as r, we get 36pi cm^2 as our exact answer. And a good approximation would be 113.1 cm^2.