Equilateral

Pronunciation: /ˌi kwəˈlæ tər əl/ ?

A polygon whose sides are the same length is called equilateral.^[1] The most commonly used equilateral polygon is the equilateral triangle. An equilateral quadrilateral is a parallelogram with equal sides. If the adjacent sides of an equilateral quadrilateral are perpendicular, the shape is a square. All regular polygons are equilateral.

The word equilateral is derived from Latin. Equi- is taken from the word aequus, meaning 'equal'. -lateral is taken from the word lateralis, meaning 'of the side'.

Click on the blue points in manipulative 1 and drag them to change the figures. No matter how you change these figures, they remain equilateral.

Examples

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now) Manipulative 1: Equilateral figures. Created with GeoGebra.

References

1. equilateral. http://wordnet.princeton.edu/. WordNet. Princeton University. (Accessed: 2011-01-08). http://wordnetweb.princeton.edu/perl/webwn?s=equilateral&sub=Search+WordNet&o2=&o0=1&o7=&o5=&o1=1&o6=&o4=&o3=&h=.
2. Carol Vorderman. Math Dictionary , pg 38. DK CHILDREN, July 20, 2009.

More Information

• McAdams, David. Equilateral Triangle. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem.org. 2009-03-12. http://www.allmathwords.org/article.aspx?lang=en&id=Equilateral%20Triangle.
• McAdams, David. Polygon. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem.org. 2009-03-12. http://www.allmathwords.org/article.aspx?lang=en&id=Polygon.

Printed Resources

Cite this article as:

Equilateral. 2010-01-25. All Math Words Encyclopedia. Life is a Story Problem.org. http://www.allmathwords.org/en/e/equilateral.html.

Translations

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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.org and are licensed under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.

Revision History

2008-12-13: Added derivation of word from Latin (McAdams, David.)
2008-11-18: Changed manipulative to GeoGebra. Added sentence on polygons (McAdams, David.)
2008-07-16: Added vocabulary links (McAdams, David.)
2008-06-07: Corrected spelling (McAdams, David.)
2008-05-10: Initial version (McAdams, David.)