What are the Vertices of a Triangle?

In geometry, a Vertex (singular) is a point where two straight lines or edges meet to form an angle. In simpler, everyday language, a vertex is the corner or the sharp point of a shape.

• Singular: Vertex
• Plural: Vertices (pronounced ver-ti-seez)

By definition, a triangle is a closed 2D polygon made of three straight lines. Because there are three lines intersecting, a triangle always has exactly 3 Vertices.

• It has 3 Edges (the straight sides).
• It has 3 Vertices (the sharp corners).
• It has 3 Interior Angles (located exactly at the vertices).

In mathematics, vertices are incredibly important because they give a shape its 'Name'.

• When you draw a triangle, you label its three sharp corners with capital letters, usually A, B, and C.
• The triangle is then officially named $\Delta ABC$.
• The straight line connecting Vertex A to Vertex B is called the Edge 'AB'.
• The angle located at Vertex A is called $\angle A$ or $\angle BAC$.