The 7 types of triangles: classification according to their sides and angles.

A geometric shape that can be subdivided according to several characteristics.

During our childhood, we all had to attend math classes at school, where we had to study the different types of triangles. However, as the years go by we may forget some of the things we have studied. For some individuals mathematics is a fascinating world, but others enjoy the world of letters more.

In this article we will review the different types of trianglesIt can be useful to refresh some concepts studied in the past or to learn new things you didn't know.

• Recommended article: "The 7 types of angles, and how they can create geometric figures".

Usefulness of triangles

In mathematics, geometry is studied, and different geometric figures such as triangles are studied in depth. This knowledge is useful for many reasons; for example: to make technical drawings or to plan a construction site and its construction.

In this sense, and unlike a rectangle that can be transformed into a parallelogram when force is applied to one of its sides, the sides of a triangle are fixed. Due to the rigidity of its shapes, physicists demonstrated that the triangle can withstand high amounts of force without deforming. Therefore, architects and engineers use triangles when building bridges, roofs on houses, and other structures. When triangles are built into structures, they increase strength by reducing lateral movement..

What is a triangle

A triangle is a polygon, a plane geometric figure that has area but no volume. All triangles have three sides, three vertices and three internal angles, and the sum of these is 180º.

The triangle is composed of:

• VertexBase : each of the points that determine a triangle and are usually denoted by capital Latin letters A,B,C.
• Basecan be any of its sides, the one opposite the vertex.
• Heightis the distance from a side to its opposite vertex.
• SidesSides : there are three sides and because of them triangles are usually classified in different ways.

In these figures, one of the sides of this figure is always less than the sum of the other two sides, and in a triangle with equal sides, its opposite angles are also equal.

How to calculate the perimeter and area of a triangle

Two measurements that we are interested in knowing about triangles are the perimeter and the area. To calculate the first one, it is necessary to add the lengths of all its sides:

P = a + b + c

On the other hand, to know the area of this figure, the following formula is used:

A = ½ ( b h )

Therefore, the area of the triangle is base (b) times height (h) divided by two, and the value resulting from this equation is expressed in square units.

How triangles are classified

There are different types of triangles, and they are classified according to the length of their sides and the amplitude of their angles.. Taking into account their sides, there are three types: equilateral, isosceles and scalene. According to their angles, we can distinguish right triangles, obtuse angles, acute angles and equiangles.

These are described in detail below.

Triangles according to the length of their sides

Taking into account the length of the sides, triangles can be of different types.

1. Equilateral triangle

An equilateral triangle has three sides of equal length, so it is a regular polygon.. The angles in an equilateral triangle are also equal (60º each). The area of this type of triangle is the root of 3 times 4 times the length of the side squared. The perimeter is the product of the length of one side (l) times three (P = 3 l).

2. Scalene triangle

A scalene triangle has three sides of different lengthsand its angles also have different measures. The perimeter is equal to the sum of the lengths of its three sides. That is: P = a + b + c.

3. Isosceles Triangle

An isosceles triangle has two sides and two equal anglesand the way to calculate its perimeter is: P = 2 l + b.

Triangles according to their angles

Triangles can also be classified according to the width of their angles.

4. Rectangular triangles

They are characterized for having a right interior angle, with a value of 90º.. The legs are the sides that form this angle, while the hypotenuse corresponds to the opposite side. The area of this triangle is the product of its legs divided by two. That is: A = ½ (bc).

5. Obtuse triangle

This type of triangle has an angle greater than 90° but less than 180°, which is called "obtuse", and two acute angles, which are less than 90°.and two acute angles, which are less than 90°.

6. Acute-angled triangle

This type of triangle is characterized because its three angles are less than 90°.

7. Equiangular triangle

It is the equilateral triangle, since its internal angles are equal to 60°.

Conclusion

Practically all of us have studied geometry in school, and we are familiar with triangles.. But over the years, many people may forget what their characteristics are and how they are classified. As you have seen in this article, triangles are classified in different ways depending on the length of their sides and the width of their angles.

Geometry is a subject that is studied in the subject of mathematics, but not all children enjoy this subject. In fact, some have serious difficulties. What are the causes of this? In our article "Children's difficulties in learning mathematics" we explain.