how do I set up a teas graph?

I need to set up a teas graph, which is a triangular graph with each axis
being a different parameter.

Found this http://sul-server-2.stanford.edu/bya...r/solpar7.html through Google. Can't comment on how the parameters are derived, but the plot appears to be a pretty standard ternary diagram. Excel doesn't have the capability built into it to rotate the Y axis (some other plotting programs do); Excel insists that the Y axis should be 90 degrees relative to the X axis. I occasionally need to plot ternary diagrams, and either use a right triangle or hide the y-axis and plot my own axes. I can't remember the transformation off hand, but the formulas for transforming square cartesian coordinates to the triangular coordinates aren't difficult to derive-- it's pretty simple geometry/trigonometry.
If you want, a google search for ternary plot in excel yields several hits that claim to have worksheets for drawing ternary diagrams.