Question

Find the circumference and the area of a circle with diameter 6 km.

Write your answers in terms of , and be sure to include the correct units in your answers.

(a) Circumference:
(b) Area:

Answer 1

Circumference: 18.85 km
Area: 28.27
`km^2`

Explanation:

We need to find (1) the circumference, and (2) the area, given a diameter of 6 kilometers. Area should be found in
`km^2` but circumference should be found in km. The radius is 3 km because the radius is half of the diameter.

(1) Finding the circumference (C)

`C = 2\pi r`

`C = 2\pi (3)`

`C = 18.849` km (round to 18.5)

(2) Finding the area (A)

`A = \pi r^(2)`

`A = 28.274`
`km^2` (round to 28.27)