dihedral angles

A dihedral angle is the angle between two flat surfaces (planes) that meet along a common edge. Imagine opening a book: the angle between adjacent pages (planes) along the spine is a dihedral angle. It measures how "spread out" or "closed" the two surfaces are relative to each other. Dihedral angles are important in geometry, chemistry, and engineering, helping describe the three-dimensional shape of objects such as crystals, polyhedra, or mechanical components. They are typically measured in degrees and can describe both the sharpness of a joint and the overall three-dimensional structure.