I followed this (poorly diagrammed) method of working out the mitre angle between faces of a pyramid and applied it to a truncated n-sided pyramid.

It seems correct because if I then create a solid and split it as if I was making it from a panel material, the result I calculate matches the angle I get when I use ANALYSE>>ANGLE and select the 2 planar faces.

BUT… if I use the face normals and calculate the angle between them I get a different answer. Is this because I don’t have the right plane input into the Angle component?

The answer I want is the mitre angle I would have to set my circular saw at to cut the edges of the panels so they fit together properly.

Why am I getting different results? I guess I’m missing some fundamental knowledge about angles in 3d?

TRUNC_PYRAMID.gh (36.6 KB)