Triangular Plot

http://en.wikipedia.org/wiki/File:Flammability_diagram_methane.png

A triangular plot or ternary plot graphically depicts the ratios of the three variables as positions in an equilateral triangle. The proportions of these three variables must sum up to a constant for this to be able to be accurately represented. This example shows the flammability diagram for methane, when there is a certain amount of methane, nitrogen and oxygen in a certain area, the flammability of that mixture increases with different ratios of the three.