Area of a circle:

We need to find the radius of the circle before we can find the area. The radius of a circle is half of the diameter. We are already given the diameter, so the radius would be 1/2d, where d = diameter.
Plug in 18 for d
.
The radius of this circle is 9 inches. Now we can plug in 9 for r in the formula for area of a circle.
(rounded to the nearest whole)
The area of the circle is 254 in².