The folks at Dengarden have a lot of conduit bending resources. If you're familiar with the way that conduit bending is usually taught, it's via shortcuts and rote memorization of how to do things like offsets, kicks, bends, etc.
Suppose you studied trigonometry in high school, as most of us did. Maybe you want to apply math that you already know to conduit bending.
The only thing I have to add to their documentation is "don't overthink this". Don't start thinking about lines through the centerline of the conduit and try to hang your calculations in the middle of the air - the only line that really matters is one that is tangent to the tube where the EMT touches the wall longitudinally. Run all your calculations based on that and everything else falls into place.