Pronunciation: /koʊˈpleɪ nər/ ?

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Manipulative 1: Coplanar and non-coplanar lines and points. Created with GeoGebra.

Mathematical objects such as points and lines are coplanar if the lie in the same plane.[1] In manipulative 1, lines A and B are coplanar with each other and with point C. Point D and line E are not coplanar with A, B, and C. Objects that are not in the same plane are called non-coplanar.

The grey parallelogram in manipulative 1 represents a portion of a plane. Click on the yellow points in manipulative 1 and drag them to change the figure. The yellow point labeled 'rotate' rotates the plane.


  1. coplanar. WordNet. Princeton University. (Accessed: 2011-01-08).
  2. Keller, Samuel Smith. Mathematics for Engineering Students, Plane and Solid Geometry, pg 118, def 8. D. Van Nostrand Company, 1908. (Accessed: 2010-01-06).
  3. Beman, Wooster Woodruff and Smith, David Eugene. Solid Geometry, pp 245-246. Ginn & Company, 1903. (Accessed: 2010-01-20).

More Information

  • McAdams, David. Plane. All Math Words Encyclopedia. Life is a Story Problem LLC. 2009-03-12.

Cite this article as:

Coplanar. 2010-01-06. All Math Words Encyclopedia. Life is a Story Problem LLC.


Image Credits

Revision History

2010-01-06: Added "References" (McAdams, David.)
2008-04-30: Initial version (McAdams, David.)

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