In every polygon, the number of sides equals the number of angles. In the triangle, there is a relationship between the measures of the sides and the measure of the angles. It should be remembered that, regarding the measure of the sides, the triangles are classified as follows:
Scalene: sides with different measurements.
Equilateral: sides with equal measures.
Isosceles: It has two sides with equal measures.
The relationship established between the sides and angles of a triangle can be observed according to the following definitions:
The scalene triangle has sides with different measurements, so the angles will have different values.
The equilateral triangle has sides with equal measurements, so the angles must have equal values.
The isosceles triangle has two of its sides with equal measurements, so two of its angles will also have equal values.
Scalene Triangle 
Equilateral triangle
isosceles triangle
by Mark Noah
Graduated in Mathematics
Brazil School Team
triangle - Math - Brazil School
Source:
Brazil School - https://brasilescola.uol.com.br/matematica/relacao-entre-os-lados-os-Angulos-um-triangulo.htm