The finite region bounded by the curve , the y-axis, and the line , is rotated through 360 degrees about the x-axis. Show that the volume of the solid formed is .
Volume = , with limits
This becomes: Volume = , with limits
(We can take pi outside the integral and multiply the result by it later).
Integrating term by term:
So my answer is:
So I don't know how they've reached the answer given.