Find the area and the circumference of a circle with radius 3km.Write your answers in terms of π, and be sure to include the correct units in your answers.

To find:
a) Area of the circle.
b) Circumference of the circle.
Solution:
a) It is known that the area of a circle is whose radius is r is given by:
[tex]Area=\pi r^2[/tex]So, the area of the given circle is :
[tex]\begin{gathered} A=\pi(3)^2 \\ =9\pi km^2 \end{gathered}[/tex]b)
It is known that the circumference of a circle whose radius is r is given by:
[tex]C=2\pi r[/tex]So, the area of the given circle is :
[tex]\begin{gathered} C=2\pi(3) \\ =6\pi km \end{gathered}[/tex]