I used the term ElectroMagnetic to present the concept because the 21cm wavelength and related frequency are well known values.
I suggest that the process that produced the symmetry is another variant of the geometric/trigonometric forms, which are plane, spherical and hyperbolic geometry, and their associated plane, spherical and hyperbolic trigonometry. I do not have a name for it.
The use of the linear and angular notation associated with transverse waveforms is "unconventional" but it results in geometric/mathematical relationships that have unusual scope. You can translate (rotate) the angle to 45 degrees and still get symmetry, but you have recognize what is and is not a variable. The relationships and numeric values that result for the 45 degree angle are actually the general case and the angle presented in the EMTriangle article is a special case.
What I was hoping to do when posting the "EM Triangle" was to elicit aid in defining the underlying mathematical relationships of the geometric structure that produced the symmetry. The process to produce the symmetry requires one element of the right triangle be "constrained" and I choose the vertical leg for the constrained element in my example, and it will always be equal to one.
The "triangle" is described in more detail in the Universal.pdf article, the only change is that I used the 21.106 cm value without its 100 multiplier. The results are still "numerically" symmetrical.
universal.pdf