- #1
armolinasf
- 196
- 0
Homework Statement
So I wanted to try and derive the surface area of a sphere with radius r. My plan was to basically integrate the circumferences of disks from 0 to r and then multiply it by 2.
The Attempt at a Solution
I got this:
4[tex]\pi[/tex]r[tex]^{2}[/tex] [tex]\int^{\pi/2}_{0}[/tex]cos[tex]^{2}[/tex][tex]\theta[/tex]
evaluating gives [tex]\pi^{2}[/tex]r[tex]^{2}[/tex] which i obviously not the SA of a sphere.
So I went on to wikipedia and read about archimedes and the proof about how you can derive the SA by the fact that its the derivative of the volume. So my question is why can't it be proven by integrating circumferences or in some similar manner?