I can't find my mistake when solving the surface area of a sphere.
Description of the sphere:
Given a sphere of radius centered at the origin. There is a circle at distance from the origin which has a radius of which is inscribed in the sphere
Description of the problem:
I was solving both the volume and area of a sphere. At first I calculated the volume of the sphere in the following approach:
(Area of the circle)
Where it calculates the area of every circle and multiplicates by the differential. No problems here.
Now I wanted to do the same for the surface area, but using the circumference length instead, therefore:
(Length of the circumference)