Kablam! Satellite collision math, and a correction

OK, so last night I posted about satellites that collided in orbit. I mentioned that the energy created in the collision was about the same as detonating a ton of TNT. I got asked how I did that math. That's no problem (well, a little one), but a bigger problem is that I screwed up the physics of the orbits. As commenter Marco Langbroek pointed out, the angle of impact I used was wrong. I forgot about the angle of the nodes. Let me explain. Both satellites were in polar orbits, more or less. One had an inclination (tilt) of about 86 degrees to the Equator -- in other words, it passed 4 degrees (90 - 86 = 4) from being directly over the Earth's poles, and the other had an inclination of 74 degrees from the Equator. I assumed that meant that the angle of approach was 12 degrees. ...