During childhood, we all had to attend math classes at school, where we had to study the different types of triangles. However, over the years, we may forget some things we studied. For some individuals, mathematics is a fascinating world, but others like the world of letters more. In this article we will provide you the types of triangles classification according to their sides and angles.

**In this article we are going to review the different types of triangles** , so it can be useful to update some concepts studied in the past or learn new things that were not known.

## usefulness of triangles

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

In that sense, and unlike a rectangle that can be turned 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 have demonstrated that the triangle can withstand large amounts of force without deforming. Therefore, architects and engineers use triangles in the construction of bridges, roofs on houses and other structures. **When building triangles on structures, resistance increases by reducing lateral movement** .

## what is a triangle

A triangle is a polygon, a flat geometric figure that has an area but no volume. All triangles have three sides, three vertices and three interior angles, and their sum is 180°

The triangle consists of:

**Vertex**: each of the points is determined by a triangle and usually indicated by capital Latin letters A, B, C.**Base**: can be any of its sides, opposite the vertex.**Height**: is the distance from one side to its opposite vertex.**Sides**: there are three, and because of this, triangles are usually classified in different ways.

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

## How to calculate the perimeter and area of a triangle

Two measurements 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**

Instead, to find the area of this figure, the following formula is used:

**A = ½ (bh)**

Therefore, the area of the triangle is the base (b) by the 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 taking into account the length of the sides and the amplitude of the angles** . Given their faces, there are three types: equilateral, isosceles and scalene. Depending on their angles, we can distinguish right triangles, obtuse angles, acute angles and equiangles.

## Triangles according to the length of the 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, making it a regular polygon** . The angles in an equilateral triangle are also equal (60° each). The area of this type of triangle is the root of 3 by 4 by the length of the square side. The perimeter is the product of the length of one side (l) by three (P = 3 l)

### 2. Scalene triangle

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

### 3. isosceles triangle

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

## Triangles according to their angles

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

### 4. right triangle

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

### 5. obtuse triangle

**This type of triangle has one angle greater than 90° but less than 180°, called “obtuse”** , and two acute angles, less than 90°.

### 6. Acute triangle

This type of triangle is characterized by having three angles less than 90°

### 7. triangle triangle

It is the equilateral triangle as its interior angles are equal to 60°.

### Conclusion

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

Geometry is a subject studied in the field of mathematics, but not all children are fond of 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 this to you.