Question

The circumference of a circle is 20π. What is the area of the circle?A. 20πB. 10πC. 100πD. 400π

Answer 1

The circumference of a circle is 20π. What is the area of the circle?



A. 20π

B. 10π

C. 100π

D. 400π

Remember that

The circumference is equal to

`C=2\pi r`

we have

C=20pi

substitute the given value and solve for r

so

`\begin{gathered} 20\pi=2\pi r \\ r=10\text{ units} \end{gathered}`

Find the Area

`A=\pi\cdot r^2`

substitute

`\begin{gathered} A=\pi\cdot10^2 \\ A=100\pi\text{ unit2} \end{gathered}`

therefore

the answer is option C