# Thread: Volume of a revolved curve

1. ## Volume of a revolved curve

Find the volume generated by revolving the region between $y = sinx$ from $[0,\pi]$ and the line $y = 0$ about the x-axis.

I keep coming up with 0 as an answer, and I know this can't be true. Can someone please tell me what I'm doing wrong?

2. Originally Posted by penguinpwn
Find the volume generated by revolving the region between $y = sinx$ from $[0,\pi]$ and the line $y = 0$ about the x-axis.

I keep coming up with 0 as an answer, and I know this can't be true. Can someone please tell me what I'm doing wrong?
Are you using $V=\int_0^{\pi}\pi(sin x)^2\,dx$?

3. Yes, I realized that I was integrating $sin^2 x$ wrong, and that I had to use the double angle formula. I came up with $\frac{\pi}{2}$

4. Originally Posted by penguinpwn
Yes, I realized that I was integrating $sin^2 x$ wrong, and that I had to use the double angle formula. I came up with $\frac{\pi}{2}$
$
\int_0^{\pi}(sin x)^2\,dx=\frac{\pi}{2}
$

$
V=\int_0^{\pi}\pi(sin x)^2\,dx
$

Multiply your answer by $\pi$