Question

A circle has an area of 78.5 square inches. What is the diameter of the circle?

Answer 1

The diameter is 10 square inches

Answer 2

The formula for the area of a circle is the following:

$A = \pi r^{2}$

where $A$ is the area and $r$ is the radius of the circle. We also know that the diameter of a circle is twice the length of the radius, so you are able to determine the radius using the above formula, and then you can double it to get the diameter.