## What types of triangles exist?

A triangle is a polygon, that is, a flat geometric figure that consists of three sides, three vertices and three angles, which add up to 180º. Triangles are classified according to their characteristics:

According to the size of its sides: Equilateral Isosceles Scalene According to the amplitude of its angles: Acutangle Rectangle Obtuseangle

## Types of triangles according to their sides

The names of the triangles according to their sides are: equilateral, isosceles and scalene. Each of them has different characteristics that we will develop below.

### Equilateral triangle

The equilateral triangle is one that is characterized by having all the sides equal. Consequently, all the angles of an equilateral triangle are 60º. The equilateral triangle is a regular polygon.

### Isosceles triangle

Isosceles triangles are characterized by having two equal sides and one different side. Consequently, it also has two equal angles.

### Scalene triangle

A scalene triangle is one that is characterized by having all its sides and angles unequal, that is, different from each other.

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## Types of triangles according to their angles

Triangles can be classified according to the width of their angles, which can be right (equal to 90º); acute (less than 90º) and obtuse (greater than 90º).

### Right triangle

Right triangles are those that are formed by one right angle and two acute angles. Therefore, the longer side is the hypotenuse.

For example, some isosceles and scalene triangles. That, however, can never happen with an equilateral triangle, since the measure of its angles is invariable.

See also Right triangle

### oblique triangle

Oblique triangles are those that are characterized by not having any right angles. In this group there are both acute angles and obtuse angles that, although they are different from each other, share this characteristic.

**Acute triangle**: are those that have three acute angles.

**Obtuse triangle:** are those that have one obtuse angle and two acute angles.

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