## Friday, September 9, 2016

### Blood Splatter Trigonometry.

The other night, there was a shooting and suicide in town.  Since this is such a small place, most everyone is related to the victim and the person who took his own life.  To make things easier for students, I showed NUMB3RS.  The episode itself was on Magic but Charlie mentioned Blood Splatter Trigonometry.  Have you heard about that topic?  I hadn't until this moment.

Blood Splatter Trigonometry uses the properties of math to determine a lot of information from just the splatter.  The size of the stain tells you about the type of energy involved.  For instance, a small stain indicates a high energy transfer while a misty looking stain could indicate an explosion or gunshot.

In addition, the shape of the splatter indicates the angle from which the blood came.  For instance, if it dropped straight down and hits at a 90 degree angle, the splatter will be circular while an elliptical indicates less than 90 degrees.  Further more, trigonometry is used to find the area of origin or location of the blood source and to find the point of convergence or where two or more blood stain paths intersect.

Cornell has a great lesson on this topic which focuses on the NUMB3RS episode and it includes three activities along with great explanations and the math equations used.

This Prezi shows the actual math involved in using the blood spatter trigonometry.  According to the presentation they can determine the origin of the blood, the weapon, the extent of the attack, and the height and dominant hand of the attacker.  There is a great chart showing what the blood looks like if its dropped from various angles and the angle involved in creating the right angle triangle to calculate things.

The scenario is set up  and the reader is taken through the process step by step to see how it is done and all the equations are shown.  It is well done and is perfect for including into a class if you want to show your students how trig is used in real life.

Finally, I found this 9 page paper which goes into this topic in more detail with wonderful examples so a teacher could easily include this during a unit on trig.  This paper goes into more detail on low, medium, and high impact, angle of impact, area of convergence and determining height.  I found the information in the paper is quite interesting.

Since I have a class doing trig, I think I'm going to schedule three or four days to cover this topic in detail so my students get to experience a real life application of trig ratios.  Check it out and enjoy.