Question

Find the area and the circumference of a circle with diameter 4cm.Write your answers in terms of π, and be sure to include the correct units in your answers.

Answer 1

Given:

Diameter of a circle is 4cm

Required:

To find the area and circumference of a given circle.

Explanation:

Given that the diameter is 4cm.

Therefore, the radius of the circle is

$\begin{gathered} r=\frac{4}{2} \\ =2cm \end{gathered}$

The formula for area of a circle is,

$A=\pi r^2$

Substitute the value of r, we get

$\begin{gathered} A=\pi2^2 \\ =4\pi \end{gathered}$

The formula for circumference of a circle is,

$\begin{gathered} C=2\pi r \\ =2\times\pi\times2 \\ =4\pi \end{gathered}$

Final Answer:

Area of a circle,

$A=4\pi$

Circumference is

$C=4\pi$