# Math Help - volume of sphere

1. ## volume of sphere

how to get to the volume of sphere with radius r using the integrals..

that's what i tried..

$\int \Pi r^2 dr = \frac{\Pi r^3}{3}$

I'm missing 4 :P

2. Originally Posted by metlx
how to get to the volume of sphere with radius r using the integrals..

that's what i tried..

$\int \Pi r^2 dr = \frac{\Pi r^3}{3}$

I'm missing 4 :P
use volumes of revolutions. rotate a semi circle of radius r in the upper half-plane, centered at the origin about the x-axis. use the disk method