Segment Addition Postulate

Pronunciation: /ˈsɛg.mənt əˈdɪ.ʃən ˈpɑs.tʃə.lət/ Explain

Click on the green points and drag them to change the figure. Place the middle point on the line between A and B. Is C between A and B?

Manipulative 1 - Segment Addition Postulate Created with GeoGebra.

The segment addition postulate states that given three points A, B and C on a line, C is between A and B if and only if AC + CB = AB. If C lies between A and B, then the sum of AC and CB equals AB. Also, if the sum of AC and CB equals AB, then C lies between A and B.

This postulate defines what it means to say "Point C is between point A and point B." If point C is not on the same line as AB, then the distance of AC plus CB is always greater than AB. So, a point can not be between two other points unless it is on the same line as the other points. If C is on the same line as A and B, but lies outside of A and B, then AC + CB > AB.

References

1. McAdams, David E.. All Math Words Dictionary, segment addition postulate. 2nd Classroom edition 20150108-4799968. pg 162. Life is a Story Problem LLC. January 8, 2015. Buy the book

More Information

• McAdams, David E.. Between. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 3/16/2010. https://www.allmathwords.org/en/b/between.html.

Cite this article as:

McAdams, David E. Segment Addition Postulate. 5/4/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. https://www.allmathwords.org/en/s/segmentadditionpostulate.html.

Image Credits

• All images and manipulatives are by David McAdams unless otherwise stated. All images by David McAdams are Copyright © Life is a Story Problem LLC and are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Revision History

5/4/2019: Changed equations and expressions to new format. (McAdams, David E.)
12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
12/6/2018: Removed broken links, updated license, implemented new markup, implemented new Geogebra app. (McAdams, David E.)
5/5/2011: Initial version. (McAdams, David E.)