We explain what geometric figures are and the ways in which they can be classified. Also, their types and some examples of these figures.
What is a geometric figure?
A geometric figure is the visual representation of a shape which can have different characteristics. It can be made up of a point, a line or a set of lines that join its points in a specific way.
Being representations, geometric figures are abstract, that is, they are the fruit of thought and, therefore, do not exist in reality. However, they can be drawn and in the physical world there are many objects that take their shapes.
Geometric figures are classified according to different criteria, such as their dimensions, shape and number of sides.
What is geometry? Geometry is the branch of mathematics that focuses on defining, characterizing and analyzing geometric figures.
See also: Two-dimensional
Types and examples of geometric figures
According to their number of dimensions, geometric figures are classified into dimensionless, linear, two-dimensional (or flat) and three-dimensional (or volumetric) figures.
Dimensionless geometric figures
Dimensionless geometric figures are those that do not have dimension, that is, they do not have length, width or depth. The point is a dimensionless geometric figure.
Linear geometric figures
Linear geometric figures are those that have a single dimension. They are lines with some orientation and a specific route. The linear geometric figures are:
- Beeline. It is a straight line.
- curved line. It is an oblique stroke.
Two-dimensional or flat geometric figures
Two-dimensional or flat geometric figures are those that have two dimensions: width and length. There are two large groups of this type of figures: the polygons and the curved figures.
The polygons. Its lines join to form closed figures. They have sides, vertices and angles. They are classified according to the number of sides they have and their shape.
Depending on the number of sides, polygons can be:
- Triangles. They have three sides and, depending on how they are, they are classified as:
- Equilateral triangles They have three equal sides.
- Isosceles triangles. They have two equal sides and one different side.
- Scalene triangles It has all different sides.
- Quadrilaterals. They have four sides and, depending on their sides and angles, they can be:
- Squares. They have four 90° angles and four equal sides.
- Rectangles. They have four 90° angles and two pairs of sides that are identical to each other.
- Rhombuses. They have four equal sides, and a pair of angles greater than 90° and another pair less than 90°.
- rhomboids. They have two pairs of equal sides, two angles less than 90° and two others greater than 90°.
- Trapeze. They have four sides and the top one is always smaller than the bottom one.
- Pentagons. They have five sides.
- Hexagons They have six sides.
- Heptagons. They have seven sides.
- Octagons. They have eight sides.
- Nonagons. They have nine sides.
- Decagons. They have ten sides.
The curved figures. They have at least one curved line. The most frequent are:
- Circles. They are figures in which all points on the line have the same distance from the center.
- Ovals or ellipses. They are like a flattened and elongated circle, because it is a symmetrical figure, but some points of the line are farther from the center.
Vocabulary of two-dimensional or plane figures:
- Side. It is each of the lines of a polygon.
- Vertex. It is the point where two sides meet.
- Angle. It is the figure that is formed when two lines come together and its amplitude is measured in degrees (°).
Three-dimensional or volumetric geometric figures
Three-dimensional or volumetric geometric figures have three dimensions: width, length and depth. Therefore, they have volume. They are classified into polyhedra and round bodies:
The polyhedra. They are made up of several flat faces, which are polygons and which are all joined together. Additionally, they have vertices and edges. For example:
- Cubes. They have six faces that are squares.
- Prisms. They have two opposite and equal bases that are polygons, and other faces that are always quadrilaterals. The number of faces is determined by the sides of the polygons that form the bases.
- Pyramids. They have a single base, which is a polygon, and faces that are triangles that join at the top to form a vertex.
- Tetrahedra. They are a type of pyramid whose base and faces are equilateral triangles.
The round bodies. They are made up of at least one face that is curved. For example:
- Spheres. They have only one face that is completely round.
- Cylinders. They have two bases that are identical circles, and a curved face that connects the two bases.
- Cones. They have a base that is a circle, and a face that detaches from the base and ends in a vertex.
Vocabulary of three-dimensional or volumetric figures:
- Face. It is each flat figure that forms a three-dimensional figure.
- Edge. It is the line where two faces meet.
- Vertex. It is the point at which three or more faces meet.
References
- Godino, JD and Ruiz, F. (2002). Geometry and its teaching for teachers. Department of Mathematics Didactics, Faculty of Educational Sciences, University of Granada.
- Medina, H. (2022). geometric figures. Encyclopedia of Mathematics. https://enciclopediadematematica.com/
- Ministry of Education of Ecuador (2016). Mathematics 8. Student text. YE. https://educacion.gob.ec/
- Universe Formulas. (2024). Geometric figures. https://www.universoformulas.com/
