Question: how to find the surface area of a unit sphere?
Answer: The surface area of an (n–1)-dimensional sphere with radius r is An rn−1 and the volume of an n-dimensional ball with radius r is Vn rn. For instance, the area is A = 4π r 2 for the surface of the three-dimensional ball of radius r. The volume is V = 4π r 3 / 3 for the three-dimensional ball of radius r.