Three forces F1, F2, and F3 act on a rigid body. Find the net torque.

Here are the solutions to the problems:

1. Three forces $\mathbf{F}_1$, $\mathbf{F}_2$, and $\mathbf{F}_3$ act on a rigid body.
Given forces and position vectors:
$\mathbf{F}_1 = \mathbf{i} + \mathbf{j} + 2\mathbf{k}$, $\mathbf{r}_1 = \mathbf{i} - \mathbf{j} + \mathbf{k}$
$\mathbf{F}_2 = \mathbf{i} - \mathbf{j} + 2\mathbf{k}$, $\mathbf{r}_2 = 2\mathbf{i} - \mathbf{j}$
$\mathbf{F}_3 = 2i + \