Pronunciation: /ˈvɜrtɛks/ ?

A vertex is a point that is the endpoint of two or more non-collinear line segments or rays.[1][2] The plural of vertex is vertices.

Examples of Vertices
Vertex of an angle.
Figure 1: Vertex of an angle.

The vertex of an angle is the point where the lines intersect that form the angle.

Vertices of a triangle.
Figure 2: Vertices of a triangle.

The vertices of a triangle are the points where the sides of the triangle intersect.

Vertices of a polygon.
Figure 3: Vertices of a polygon.

The vertices of a polygon are the points where the sides of the polygon intersect.

Vertices of parabolas.
Figure 4: Vertices of parabolas.

A vertex is also the inflection point of a parabola or a polynomial. This is the point where the curve changes direction.


  1. vertex. WordNet. Princeton University. (Accessed: 2011-01-08).
  2. Keller, Samuel Smith. Mathematics for Engineering Students, Plane and Solid Geometry. D. Van Nostrand Company, 1908. (Accessed: 2010-01-02).
  3. Casey, John, LL.D., F.R.S.. The First Six Books of the Elements of Euclid, pg 7. Casey, John, LL.D. F.R.S.. Hodges, Figgis & Co., 1890. (Accessed: 2010-01-02).

Cite this article as:

Vertex. 2010-01-01. All Math Words Encyclopedia. Life is a Story Problem LLC.


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Revision History

2010-01-07: Added "References" (McAdams, David.)
2008-10-11: Added vertex of a polynomial (McAdams, David.)
2008-06-07: Corrected spelling (McAdams, David.)
2008-04-23: Initial version (McAdams, David.)

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