Types of triangles, by sides and angles.

This article will be about The different types of triangles there are, taking as criteria angles and sides. Isosceles, scalene, equilateral, right and oblique triangles.

Before we start with the list of the different types of triangles we are going to remind the basic concept of triangle: A triangle is a geometric figure of 2 dimensions that is formed by three lines, each point of intersection between the sides (vertex) form an angle, therefore a triangle has 3 sides and 3 angles.

There are two main criteria to classify a triangle, by sides and by angles, but these two types of classification can be put together and form a more specific description of the triangle we are talking, in this article we are going to classify the triangles based on these 3 criteria, by sides, by angles and by sides and angles.

Equilateral triangle

Is a triangle that has 3 sides of the same length, besides having the sides of the same length it also has 3 angles equals to 60°.

Isosceles triangle

Is a triangle that has 2 sides of the same length, and it also is going to have 2 angles with the same inclination, the degrees of the two angles does not have a specific measure, as long as the sum of the three angles is not greater than 180°.

Scalene triangle

Is a triangle that has 3 sides of a different length each, because of this, the angles are going to be different as well.

Right triangle

We denominate a right triangle to a triangle that has a 90° angle, is important to know that a right triangle can only have one 90° angle. A right triangle has a special way to call its sides, the greater side is known as “hypotenuse”, while the other two sides are called “legs”.

The right triangle is doubtless the most used triangle of all, it is used in multiple branches of physics and mathematics because of its characteristics that help in a big way the resolution of other problems that hardly have do with geometry. To know more about this triangle visit our article of trigonometry.

Oblique triangles

An oblique triangle is any triangle that does not have a 90° angle, this means that any triangle that is not a right triangle is an oblique triangle.

An oblique triangle is sub divided in 2 types of triangles: the obtuse triangle and the acute triangle, an obtuse triangle is a triangle that has an angle greater than 90° and an acute triangle is the one that has every angle less than 90°.

Scalene right triangle

Is the triangle that is formed by three sides of different length and has a 90° angle.

Scalene acute triangles

Is a triangle that has 3 different sides and every angle is less than 90°, or that every angle is acute.

Scalene obtuse angle

Is a triangle with 3 different sides and has an angle greater than 90°.

Isosceles right triangle.

Is a triangle that has a 90° angle and its legs (the sides that form the 90° angle) have the same length.

Isosceles acute triangle

Is a triangle which angles are less than 90° and this has two sides of the same length.

Isosceles obtuse triangles

Is composed by 2 sides of equal length and one of the angles is greater than 90°.

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