Surface Area of Sphere

Definition of a Sphere

A sphere is a geometrical object, where every point on the surface is equidistant to a point within the sphere (aka Centre).

Formula for Surface Area

Surface Area of a Sphere = 4πr³

where r is the Radius of the Sphere.

Projection of Sphere onto a Cylinder

As we make the 'rectangular' strips smaller, the projected area from the sphere gets closer to that of the image on the cylinder. Watch the 3B1B video attached for the proof.