Question

The area of a circle is 4pi square centimeters . What is the circumference?

Answer 1

The area of a circle can be calculated as

$A=\pi r^2$

And the circumference can be calculated as

$C=\pi\cdot2r$

We know that the area of this circle is 4π cm²

From this we can calculate the length of the radius from the formula

$\begin{gathered} A=\pi r^2 \\ 4\pi=\pi r^2 \\ \frac{4\pi}{\pi}=r^2 \\ 4=r^2 \\ \sqrt[]{4}=\sqrt[]{r^2} \\ 2=r \end{gathered}$

Now that we know the radius we can calculate the circumference of the circle

$\begin{gathered} C=\pi\cdot2r \\ C=\pi\cdot2\cdot2 \\ C=4\pi \end{gathered}$

The circumference od the circle is 4π cm= 12.57cm