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 \\ (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