I don't know how to start.
The formula for the area of a circle is π r2 . This means that radius of the given circle is sqrt(16) = 4 inches
Consequently, the diameter of the circle is 8 inches. This means that the diagonal of the largest possible inscribed square is also 8 inches. From the Pythagorean theorem, we figure the side of the largest square to be (8 inches)/sqrt(2). Since the area of a square is (length of side)2 , the are of the square is 32 inches2 .