...intercept the meaning of the theorem...

Thanks Hans for your theorem interception, very useful. I think you mention something about doing the math in your much used roof guide. So as a hint, I took the liberty of putting a pointer to various calculations in SourceForge, feature-requests 684.

Maybe it is worth making a list of the most useful calculations for all of us who where not subjected to French maths in school? For instance, how to calculate the values indicated here, and probably a few more that I did not think of:
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