Question

Find the area and the circumference of a circle with diameter 8cm.Write your answers in terms of π, and be sure to include the correct units in your answers.

Answer 1

We need to find the circumference and the area of a circle with a diameter of 8cm.

We know that the radius is half the diameter. Thus, the radius r of this circle is:

`r=\frac{8\text{ cm}}{2}=4\text{ cm}`

Now, the circumference C is given by:

`\begin{gathered} C=2\pi r \\ \\ C=2\pi(4\text{ cm}) \\ \\ C=8\pi\text{ cm} \end{gathered}`

And area A is given by:

`\begin{gathered} A=\pi r^2 \\ \\ A=\pi(4\text{ cm})^2 \\ \\ A=16\pi\text{ cm}^2 \end{gathered}`

Therefore:

`\begin{gathered} \text{ Circumference: }8\pi\text{ cm} \\ \\ \text{ Area: }16\pi\text{ cm}^2 \end{gathered}`