The Greek word dihedrons came to Castilian as dihedral, a concept that is used in the field of geometry. The space portions that are limited by a pair of half-planes originating from the same line are called dihedral angles.
To represent a dihedral angle, it is necessary to resort to two parallelograms that have a side in common. These figures allow us to symbolize the two semi-planes that, starting from the same edge, give rise to this class of angles.
Let us remember that the parallelogram is defined as a quadrilateral (a polygon that has four sides and four vertices) with the characteristic that its two pairs of opposite sides are equal and parallel. We understand by opposite sides, worth the clarification, those that do not have a vertex in common. The appearance of the parallelogram is very particular, since it looks like a square that has been deformed; in fact, the most common graphic editing programs have the option of altering images in this way to achieve different effects.
The other concept that appears related to the dihedral is the edge, which also belongs to the field of geometry. It is a line segment whose objective is to limit the side (or face ) of a plane figure. In the branch of geometry known as geometry of space, which studies the figures with volume that occupy space, we speak of edge to name the segment in which two faces meet.
From an auxiliary plane that is perpendicular to the straight line of origin, the dihedral angle is obtained, whose value is equal to the amplitude reached by the smallest angle produced by the half-lines belonging to the different half -planes .
In short, it can be said that a dihedral angle is a spatial region formed by two half-planes with a common straight line. The faces of the angle are said half-planes, while its edge is the aforementioned common straight line. The measure, meanwhile, is the smallest of its rectilinear angle.
According to their angles, it is possible to differentiate between a concave dihedral and a convex dihedral. Convex dihedrals, in turn, can be obtuse, right, or acute. On the other hand, depending on the characteristics of their rectilinear angles, we can speak of supplementary dihedrals and complementary dihedrals.
Given the limitations of the tools available to students and teachers in the classrooms of schools and colleges, the representation of the dihedral angles on paper and on the blackboard is not usually done with the pertinent deformation that perspective would cause in the semi- planes, but which are drawn axonometrically.
The system for graphically representing figures known by the name of axonometric perspective consists of using a cylindrical or parallel projection to draw volumes or geometric elements on a plane, in such a way that their proportions (their height, their length and their width) are kept at the same level. along each of the three axes on which it is projected.
In other words, in the geometry books and in the sources that we find on the Internet, the graphic representation of the concept of dihedral does not have a realistic perspective, that is, the one that an object would have in the real world. Thanks to this resource, it is possible to measure the sides of the half-planes and the extension of the edge regardless of their distance from the observer, since the result is always the same.
The notion of dihedral can also be found in other fields beyond geometry. A climbing center in the Chilean city of Iquique, a decoration house in Madrid ( Spain ) and a technology company in Zaragoza have this term in their name.
List of Acronyms Related to Dihedral
| Acronym | Meaning |
| DASSD | Dihedral Angle and Secondary Structure Database of Short Amino Acid Fragments |
