Pronunciation: /ˌpɜr pənˈdɪk yə lər/ ?

Lines are perpendicular if they make a right angle where they intersect[1][2].

Lines that are perpendicular.
Perpendicular lines Perpendicular lines
Lines that are not perpendicular.
Non-perpendicular lines Non-perpendicular lines Parallel lines


  1. Keller, Samuel Smith. Mathematics for Engineering Students, Plane and Solid Geometry, pp 3, 64-65. D. Van Nostrand Company, 1908. (Accessed: 2010-01-02).
  2. Casey, John, LL.D., F.R.S.. The First Six Books of the Elements of Euclid, pg 7. Casey, John, LL.D. F.R.S.. Hodges, Figgis & Co., 1890. (Accessed: 2010-01-02).
  3. perpendicular. WordNet. Princeton University. (Accessed: 2011-01-08).

More Information

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

Cite this article as:

Perpendicular. 2009-12-21. All Math Words Encyclopedia. Life is a Story Problem LLC.


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Revision History

2009-12-21: Added "References" (McAdams, David.)
2008-09-02: Expanded 'More Information' (McAdams, David.)
2007-07-12: Initial version (McAdams, David.)

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