Use the formula
A = d2
for the surface area A of a sphere whose diameter measures d. This formula yields the surface area in square units.
The Hoberman Sphere is a mechanical toy that expands from 5.9 inches in diameter when it is fully closed, to 30.1 inches in diameter when fully expanded.† What is the difference in the surface area of a Hoberman sphere from when it is fully closed to when it is fully expanded (in in2)? Round the result to three decimal places
