Angle of the plane of a dihedral angle without angles

Plane angle of dihedral angle:Two faces form a dihedral angle ，，，， there is a third face perpendicular to the two faces cross over, the angle formed on this third face is called the plane angle of the dihedral angle ~~~ is also the dihedral angle we are looking for ~~~ this is from the definition ~

Non-pronged Dihedral Angle:The simplest example ~~~ 2 triangles, the 2 have a vertex overlap ~ and the sides do not overlap, the 2 sides do not overlap, and the 2 sides do not overlap. Since the plane is infinitely extended, a dihedral angle can be formed at this point ~~~~~

Surface meaning is that there is no common **** prongs of the dihedral angle~~~ If you make up your own surface ` you can draw it as the common kind of dihedral angle with common **** prongs~~~ Easy to solve the problem