How many square inches are in a 8 inch diameter circle?

Answer 1

8/2 is 4, the radius

pi*r^2

PI r^2

3.14159 * 16= 50.27 sq inches

Here are the formulas for determining the area of a circle when you have either the radius or the diameter:

Note that the radius of a circle is half the length of the diameter, so the following functions are accepted.

PI * Radius^2

or

PI/4 * Diameter^2

For your question, I'll use the second function. The diameter given is 8", so:

[(3.1416/4)] * (8 * 8) = 0.7854 * 64 = 50.27 square inches