In order to understand the meaning of the term irregular polygon, it is necessary that, first of all, we proceed to determine the etymological origin of the two words that give it its shape:
-Polygon derives from Greek and is the result of the sum of two components in that language: "Poli", which can be translated as "many", and "gono", which is synonymous with "angle".
-Irregular, for its part, emanates from Latin. In your case, it is a derivation of “irregularis”, which is obtained from the union of the negation prefix “in”, the noun “regula” (“straight bar to measure”) and the suffix “-alis”, which it is used to indicate "quality".
A polygon is a geometric figure, of a plane type, that is developed by joining a certain number of segments called sides.
Polygons can be classified in different ways according to their characteristics. When their sides and internal angles are not equal (that is, they are not congruent with each other), we can speak of irregular polygons. On the other hand, if the internal angles and the sides of the polygon are equal, the figure will be classified as a regular polygon.
In addition to the above, it is important to note that every irregular polygon is made up of the following elements:
-Interior angles.
-Interior point, which comes to be that which is within the perimeter of the polygon.
-Vertices, which are the points where the sides meet.
-Sides, which are the segments that delimit the perimeter of the aforementioned polygon.
Due to its characteristics, it can be said that the vertices of irregular polygons cannot be included in the same circle. Like any other polygon, they can be named differently according to the number of sides: irregular pentagon (if it has five sides), irregular quadrilateral (four sides), irregular triangle (three sides), etc.
To calculate the perimeter of an irregular polygon, it is necessary to add the lengths of all its sides. Take, for example, the case of an irregular polygon with three sides. This irregular triangle can have a first side measuring 10 centimeters, a second side measuring 16 centimeters, and a third side measuring 12 centimeters. Its perimeter, therefore, will be 38 centimeters.
In the same way, we must not ignore the fact that to know the area of an irregular polygon there is another method that responds to the name of triangulation. What does it consist of? Basically in dividing the one into triangles and calculating the areas of these to, finally, make the sum of all of them.
And all this without forgetting that there is also the Gaussian determinant method, which is used to calculate the area from a Cartesian plane.
A simpler way to understand which are irregular polygons is to think that this classification includes all those polygons that do not have equal sides and angles, regardless of how many they have. All polygons that do not comply with this property, therefore, will fall into the group of regular polygons.