That analytical approach is how engineers are trained and you were not sleeping in class.Thank you Rich, the above method requires no math, no miter saw and no angle finder.
It is merely an analytic approach to solving a difficulty with miter joints on veneer.
The math was my generic and incorrect term for the arithmetic demonstrated in you posting. Yep, a carpenter with a variable angle tool could do the same thing. Another framers tool is the square with dimensions for various rise/run conditions. Takes me back to the fun days of analog slide rules where the first challenge was to learn "slide right" to keep track of the number and decimal point. Students now possibly don't know what a "safety factor" is that we always applied in our structural calcs. For trusses with compression and tension members where I occasionally got lost in the cacls I followed the professors advise, "If you get lost or stymied just ask your wife or girl friend to look at the truss and loading, she will tell you what the member is doing by inspection" 
Good visual explanation on your corner. 
Rich
Rich
