Crown Molding - What is the proper Spring Angle? I am installing crown molding in my house, we own 9 foot...

I am installing crown molding in my house, we own 9 foot ceilings. What is the proper spring angle for 9 foot ceiling? I know the standard sizes are 38กใ, 45กใ and 52กใ. I know it's probably 38กใ or 45กใ, but I'm not sure which. Any advice?
Answers:    True crown molding usually extends further on the wall, later the ceiling. That's what gives the 52 and 38 level angles, that add up to 90. A suitable miter saw will have the angles tarnished on the angle scale. Both on the table and the bevel compute. Look for a circle or triangle designation. You cut the angles with the stock lying flat on the saw table.
Above seem to be the "old fashion" answer. You really shold cut it upside down and backwards beside the crown molding bedded the same track it is going to bed on the wall. If you cut upside down and backwards, you really shouldn't have to verbs about the spring angel. Hope this help!