I understand that if I want to find the angle between 2 planes, I can find it via the dot products between normal vectors of those 2 planes. In such case, the result can yield acute angle or obtuse angle depending on what sign we used for the normal vectors. I also understand that its perfectly fine since when 2 planes intersect they can have both acute and obtuse angles anyway.
However, my question is in the case of angle between 2 sides of polyhedral ie the dihedral angle. Unlike planes, the angle between the 2 sides cant be both acute and obtuse at the same time. Suppose that I try to find the equations of the plane of the 2 sides, how would I know if the angle should be acute or obtuse? How do I know that I didnt pick the “wrong” normal vectors to calculate with?
Thank you! I was a long-time lurker and I would greatly appreciate your help!