Interior Angle

Pronunciation: /ɪnˈtɪər i ər ˈæŋ gəl/ ?

1

Polygon with exterior and interior angles labeled.
Figure 1: Interior angle of a polygon.

The interior angle of a polygon is the angle on the interior at a vertex of the polygon.[1] Note that the sum of the measure of an interior angle of a polygon and the measure of the corresponding exterior angle is 180° or π radians.

2

Parallel lines with an intersecting line with exterior and interior angles labeled.
Figure 2: Interior angle between parallel lines.

When two parallel lines are intersected by a third line, the angles on the inside of the parallel lines are the interior angles. Note that the sum of the measure of the interior angle and the measure of the corresponding exterior angle is 180° or π radians.

References

  1. interior angle. merriam-webster.com. Encyclopedia Britannica. (Accessed: 2010-02-18). http://www.merriam-webster.com/dictionary/interior angle.
  2. Casey, John, LL.D., F.R.S.. The First Six Books of the Elements of Euclid, pp 8,28-29. Casey, John, LL.D. F.R.S.. Hodges, Figgis & Co., 1890. (Accessed: 2010-01-02). http://www.archive.org/stream/firstsixbooksofe00caseuoft#page/8/mode/1up/search/interior.
  3. Williams, Cora Lenore. Syllabus of Plane Geometry, pg 14. (Accessed: 2010-02-18). http://www.archive.org/stream/syllabusofplaneg00willrich#page/14/mode/1up/search/interior.
  4. Noetling, William. Elements of Constructive Geometry, Inductively Presented, pg 13. Silver, Burdett & Company , 1897. (Accessed: 2010-02-18). http://www.archive.org/stream/elementsofconstr00noetrich#page/13/mode/1up/search/interior.

More Information

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

Printed Resources

Cite this article as:


Interior Angle. 2010-02-18. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/i/interiorangle.html.

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Revision History


2010-02-18: Added "References" (McAdams, David.)
2008-08-12: Added definition 2, added dictionary.com to 'More Information' (McAdams, David.)
2008-06-07: Corrected spelling (McAdams, David.)
2008-06-04: Initial version (McAdams, David.)

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