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

Answer:

$r =\frac{D}{2}=\frac{18mm}{2}= 9mm$

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

Step-by-step 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:

$r =\frac{D}{2}=\frac{18mm}{2}= 9mm$

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