# Vertex

Pronunciation: /ˈvɜr.tɛks/ Explain

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

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

The vertex of an angle is the point where the lines intersect that form the angle. Figure 2: Vertices of a triangle.

The vertices of a triangle are the points where the sides of the triangle intersect. Figure 3: Vertices of a polygon.

The vertices of a polygon are the points where the sides of the polygon intersect. 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. McAdams, David E.. All Math Words Dictionary, vertex. 2nd Classroom edition 20150108-4799968. pg 189. Life is a Story Problem LLC. January 8, 2015. Buy the book
2. Keller, Samuel Smith. Mathematics for Engineering Students, Plane and Solid Geometry. www.archive.org. D. Van Nostrand Company. 1908. Last Accessed 1/2/2010. http://www.archive.org/stream/mathengineer00kellrich#page/1/mode/1up/search/vertex. Buy the book
3. Casey, John, LL.D., F.R.S.. The First Six Books of the Elements of Euclid. pg 7. Translated by Casey, John, LL.D. F.R.S.. www.archive.org. Hodges, Figgis & Co.. 1890. Last Accessed 1/2/2010. http://www.archive.org/stream/firstsixbooksofe00caseuoft#page/7/mode/1up/search/vertex. Buy the book

McAdams, David E. Vertex. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/v/vertex.html.

### Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)