Question

. A certain coin is a circle with diameter 18 mm. What is the exact area of either face of the coin in terms of p?

Answer 1

`r =(D)/(2)=(18mm)/(2)= 9mm`

The area is given by:

`A= \pi r^2`

And replacing we got:

`A=\pi (9mm)^2 =81\pi mm^2`

So then we can conclude that the area of the coin is
`81\pi` mm^2

Explanation:

For this case we know that we have a coin with a diamter of
`D =18mm`, and by definition the radius is given by:

`r =(D)/(2)=(18mm)/(2)= 9mm`

The area is given by:

`A= \pi r^2`

And replacing we got:

`A=\pi (9mm)^2 =81\pi mm^2`

So then we can conclude that the area of the coin is
`81\pi` mm^2