Coach LouAllen's Forensics class made fake blood to use in blood spatter analysis. Using Trigonometry revealed the angle of impact of the blood relative to the surface. Once averages of spatters were found they were plugged into the formula. The formula used was: sin-1(w/l).
Also POI or point of impact can be traced by lining up the "tails" of multiple spatter patterns.
Examples can be seen hanging at the end of the Science hallway.