A black triangle

A triangle is a shape, or a part of two dimensional space. It has three straight sides and three vertices. The three angles of a triangle always add up to 180° (180 degrees). It is the polygon with the least possible number of sides. A triangle with vertices A, B, C is written as \displaystyle{ \triangle ABC }. The study of geometry related to triangles is called trigonometry. Modern computers usually use triangles to make more complex graphic images or shapes.