Incline is basically a synonym for slope or angle.

The translate (“tra”) subcommand of the sweep (“swep”) operation takes a vector dx dy dz as an argument. Since the displacement in the y direction is zero, only dx and dz matter in this case.

For two vectors to be parallel, the ratio between the components should be the same. For the one vector, dz/dx = 0.04, while for the other it’s 0.4.

In this case, dz/dx is the tangent of the angle between the displacement vector and the plane z=0.