Torque on a line

I need to calculate the torque of a line in 2D of length $L_0$.

We choose $0leq xleq L_0$, and then the pivot point is in $x=L_p$.

We have a force vectorial $F$ acting on the line.

For me, the torque is

$$(-sintheta,costheta)cdotint_0^{L_0}F(x)|x-L_p|dx$$

but in the book appears

$$(-sintheta,costheta)cdotint_0^{L_0}F(x)(x-L_p)dx$$

Why is this difference?

$theta$ is the slope of the line.