Question

How do you find the circumference and area of a circle with diameter of 12 inches?

Answer 1

The circumference of a circle is `S=2pir` where r =radius
The area of cirlce is `A=pir^2`
The diameter is twice the radius `d=2r=>r=6`

So the circumference is `S=12pi` inches
And the area `A=36pi`

Answer 2

`C=38"in"`
`A=113"in"^2`

Explanation:

To find circumference when diameter is known, use the equation `C=pixxd`

`C=pi*12"in"=38"in"`

To find the area of a circle, use the formula `A=pi*r^2`, where `r` is the radius, which half of the diameter. `r=1/2d=1/2*12"in"=6"in"`.

`A=pi*(6"in")^2"="113"in"^2`