Many of the objects that are of daily use are formed by geometric figures , even creations of nature seem capriciously made according to the rules of this discipline. These forms are recognizable if we learn what their names are and understand the criteria by which they are classified, something that we are about to do next to refresh our memory.

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What are geometric figures
? We call “geometric figure” the forms made up of sides and closed by points, which maintain a fenced space .
They can have no dimension, have only one dimension, or become two-dimensional (height and width). In case they reach three dimensions, they are called “geometric bodies” , but we will not deal with them since today we will talk about those that are flat. Let’s see it in more detail.

Types of basic geometric figures
If we leave aside the three-dimensional ones, the rest of the basic geometric figures of 1 dimension are:

1.
Single point representative of zero dimensions that we find in geometry, because it lacks width and height. It is also the essential particle that allows the configuration of the rest of the geometric figures, since these are composed of infinite points.

2. Lines, segments and curves
The straight line is composed of points arranged in succession and aligned without curving in any place.
On the other hand, the segment is a straight line fragmented in one of its sections between the two extremes that delimit it.
Contrary to lines and segments, the curved line is a succession of non-aligned points that are curved in some way.

Types of two-dimensional geometric figures
As if it were a special episode of Sesame Street, let’s analyze how they are classified according to their number of angles and sides. As we will see, the proper name of these polytopes already gives us an idea of ​​their nature .

3. Triangles
Geometric figure with three sides and three vertices where each line joins. The total of the angles that form the triangle add up to 180 , which is equivalent to a straight line.
If they are classified according to the length of their sides, we have:

3.1 Equilateral
All their sides are equal , consequently their angles will also be equal.

3.2 Isosceles
Two equal sides and two equal angles .

3.3 Scalene
None of its sides or angles are the same measure .
Another way to classify this geometric figure is by observing the extension of its angles.

3.4 Acute Angle
Its three angles are all less than 90º .

3.5 Rectangle
A single right angle (90º).

3.6 Obtuse
This type of triangle consists of two 90º angles (acute) and a third that does not reach 180º .

3.7 Equiangular
Another way of calling the triangle equilateral , but considering its angles (all 60º), the result of the fact that the three sides are also equal.

• Learn more about triangles: The 7 types of triangle (according to angles and sides).

These polygons all have 4 sides , although depending on their length and the amplitude of the angles that compose them, they will receive one name or another:

4.1 Parallelograms
The characteristic of these primary geometric figures is that two of their sides and angles are equal and are parallel to each other. Without losing sight of this, we will have the following:
Square: consists of four sides of the same length and four 90º angles (all of them straight).
Rectangle: Although it has 4 right angles, two of the sides are longer than the rest, unlike the square.
Rhombus: this parallelogram is formed by four sides of the same length, but in its case, two angles are wider than the others .
Rhomboid: a mixture of everything. Rhomboids have two adjacent sides of different lengths and two angles that are larger than two smaller ones.

4.2 Trapezoids
This quadrilateral has two parallel sides and irregular angles.

4.3 Trapezoids
None of its sides are equal , so there will be no parallels nor will its 4 angles be equal.

More examples of geometric figures
From here, we can add sides to these geometric figures. In case all its angles are right, we will speak of “regular” and “irregular”, if one or several differ.

5. Pentagon
This polygon has five sides and angles . If it is regular, each of its angles will be 108º.

6.
Hexagon If we add a line, we will have a hexagon, a polygon with six sides , with angles of 120 degrees.

7. Heptagono
Polygon of seven sides and angles , of almost 129º each one.

8. Octagon
Eight sides and angles (of 135º each of them if they are equal).

Geometric figures composed of curves
We have not forgotten the curved lines. These are the geometric figures that we can form with them:

9. Circumference
Curved, flat and closed line in which any of its points is at the same distance from the center .

10. Circle
It refers to the entire perimeter that is delimited within the contour of the circumference.

11. Semicircle
If we cut a circle in half , we have two exactly equal semicircles.