The first thing we are going to do, before entering fully into establishing the meaning of the term quadrilateral, is to determine its etymological origin. In this sense, we can say that it is a word that emanates from Latin, from the word “quadrilaterus” which can be translated as “having four sides”. She, in turn, is made up of two clearly differentiated parts:

• “Quadri”, which comes from “quattuor” and is synonymous with “four”.

• “Latus”, which means “side”.

**Quadrilateral** it’s a **concept** which is used to name that which has **four sides**.

It must be borne in mind that within the field of geography the term quadrilateral that now concerns us is used. Specifically, it speaks, for example, of what has been called the Bohemian Quadrilateral, which is a space determined by four mountain cores and that in the past came to form what was the historical border of the Countries. Czechs.

Those four mountain groups are the Ore Mountains, the Bohemian Forest, the Sudeten Mountains and the Giant Mountains.

Its most frequent use is in the **geometry**. A quadrilateral, in this sense, is a **polygon** whose sides are four. This means that the quadrilateral is determined by four segments that make it up.

Having four sides, all quadrilaterals also have two diagonals, four vertices, and four interior angles. These characteristics are maintained beyond the **form** of the ring, which can vary.

The **squares**the **rhombuses** and the **rectangles**for example, are quadrilaterals: they therefore have four sides, four **vertex**, four internal angles and two diagonals. However, it is clear that the shape of these three geometric figures is not identical.

What varies in quadrilaterals with respect to their shape is the arrangement of their sides; The points to take into account to establish a classification of quadrilaterals is the parallelism of their sides, as well as the **length** of each and their interior angles. Based on these variables, it is possible to distinguish between the following types:

*** parallelogram**: its opposite sides, that is, those whose vertices do not touch, are parallel;

*** square**: it is the simplest figure of all, both when making calculations on it and drawing it, even for people who do not have specific knowledge of geometry or **math** usually. All the sides of a square are equal, as well as all its interior angles (which are 90 degrees and are called *straight*) and its diagonals (which not only coincide in their measure but are perpendicular to each other). Finally, the square is a figure belonging to the group of **bisectors**which means that it can be divided into two equal parts, and has **circumference** inscribed, that is, it is interior and tangent to each of its sides;

*** rhombus**: it is similar to the square, since it also has four equal sides, but its interior angles are not right, but two are acute and two are obtuse, and each pair coincides in measure. Their diagonals, on the other hand, are different, one being larger than the other, although they are also perpendicular to each other. The rhombus, as well as the **square**is a bisector and has an inscribed circle;

*** rectangle**: its parallel sides, those that do not share vertices, are equal to each other. In the same way as the square, its interior angles are right and all its diagonals measure the same, although in this case they are not perpendicular to each other, given the differences in their sides. Its circumference, unlike the previous figures, is circumscribed, which means that it is external and passes through all its vertices, instead of being **tangent** at his sides;

*** rhomboid**: its two smaller sides and its two larger sides are equal to each other;

*** trapezoid**: only two of its sides are parallel and it can be **rectangle** (one of its sides is perpendicular to its bases, two of its internal angles are right, one obtuse and one acute), **isosceles** (its non-parallel sides measure the same, it has two acute angles and two obtuse angles equal to each other) or **scalene** (its four internal angles are different).

Outside of geometry, it is known as a quadrilateral when **boxing ring** and to other spaces destined to host a struggle for **sports**. As it can be assumed, the quadrilateral has four sides, which are delimited by ropes, wires or other materials. For example: *“The Uruguayan boxer promised that he will end up standing in the ring”*, *“The hook to the jaw threw the American out of the ring”*, *“If you’re scared, you can’t get in the ring”*.

Among the most important rules that boxers must comply with inside the ring, the following stand out:

• The size of the ring must be at least 7.3 meters on each side.

• Each round has a time of 3 minutes.

• Hits from the waist down are not allowed.

• If a boxer falls, he must get up without anyone’s help within a maximum period of ten seconds in order to continue the fight.

Nor should we forget that in the Tenerife city of La Laguna, Cuadrilátero is the name given to the most important nightlife area. It is made up of all kinds of bars, discos, pubs…