# Math Help - sine integral

1. ## sine integral

integration x sin x dx

2. Originally Posted by mindblowing
integration x sin x dx
You can do this by parts:

$u=x$ and $\,dv=\sin x\,dx$

Thus, $\,du=\,dx$ and $v=-\cos x$

Now I leave it for you to plug it into the integration by parts formula and simplify:

$\int u\,dv=uv-\int v\,du$

Can you take it from here?

--Chris

3. Originally Posted by mindblowing
integration x sin x dx
$\int x \sin x dx = \int x \left( -\cos x \right)' dx = -x\cos x - \int (x)'(-\cos x) dx = -x \cos x + \sin x + k$