How do I find the surface area of x^2 + y^2 + z^2 = 4 within the cylinder x^2 + y^2 = 15?
Huh? Since the radius of the sphere is 2,
and the radius of the cylinder is almost 4,
and both shapes have center at (0,0,0),
the entire sphere is within the cylinder.
Just use the normal A = 4 pi r^2 for the area