Pronunciation: /əˈdʒeɪ.sənt/ Explain

Two features on a shape are adjacent if they are next to each other.[1]

Adjacent parts of a polygon

Quadrilateral showing adjacent sides and angles
Figure 1 - Polygon

In the polygon in figure 1:

  • the angles A and B are adjacent,
  • the sides g and h are adjacent, and
  • angle A is adjacent to side g.


  • angle A is not adjacent to angle C,
  • side g is not adjacent to angle D, and
  • sides g and i are not adjacent.

Adjacent Angles on Intersecting Lines

Click on the blue points to change the figure. Click on the check boxes to turn pairs of adjacent angles red.

Which of the angles are adjacent (share a ray)?
Manipulative 1 - Adjacent Angles Created with GeoGebra.

Given two intersecting lines, two angles formed by the intersecting lines are adjacent if they are on the same side of one of the lines.

Adjacent Arcs

Click on the blue points and drag them to change the figure.

Which of the arcs are adjacent (share an endpoint)?
Manipulative 2 - Adjacent Arcs Created with GeoGebra.

Two arcs of the same curve are adjacent if they share an endpoint.


  1. McAdams, David E.. All Math Words Dictionary, adjacent. 2nd Classroom edition 20150108-4799968. pg 11. Life is a Story Problem LLC. January 8, 2015. Buy the book

Cite this article as:

McAdams, David E. Adjacent. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC.

Image Credits

Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
6/12/2018: Removed broken links, changed Geogebra links to work with Geogebra 5, updated license, implemented new markup. (McAdams, David E.)
10/12/2010: Added "Adjacent angles on intersecting lines" and "adjacent arcs". (McAdams, David E.)
12/24/2009: Added "References". (McAdams, David E.)
7/12/2007: Initial version. (McAdams, David E.)

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