:mathfacepalm:
Everyone is right, no one is wrong, we have two formulas that describe the same scenario.
The Pythagorean Theorem works perfectly fine in this case alone where you have a right-angle triangle and want to find the length of the longest side.
Extone's sine/cosine formula can be used to find the length of ANY angled slope, be it a 45° slope or a 72.683° slope.
But punching in 0.707... is hard and may end up looking weird, so rounding that up to a nice fractionable number like 0.75 like in Hipshot's chart is a good approximation.
Now if anyone can come up with a formula for texturing a face that has been cut using a 3-point clip, I'll be impressed because I clearly wasn't paying enough attention back in school to be able to do that still.

[size=85][url=http://gtkradiant.com]GtkRadiant[/url] | [url=http://q3map2.robotrenegade.com]Q3Map2[/url] | [url=http://q3map2.robotrenegade.com/docs/shader_manual/]Shader Manual[/url][/size]