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Concept

Triangle

A triangle is a polygon with three angles and three sides. The symbol is used to algebraically denote a triangle. Next to this symbol, the three vertices of the triangle are written in any order. For example, and both denote the triangle whose vertices are and
Interactive triangle with movable vertices
Triangles can be classified either according to their side lengths or to their internal angle measures.
Interactive triangle with a movable vertex
The following table lists all the different types of triangles according to their corresponding classification.
Classification of Triangles
By Angle Measures By Side Lengths
Acute Triangle Scalene Triangle
Right Triangle Isosceles Triangle
Obtuse Triangle Equilateral Triangle
Equiangular Triangle