Interior Angle
Pronunciation: /ɪnˈtɪər.i.ər ˈæŋ.gəl/ Explain
1 

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.^{[2]} 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 

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
 interior angle. merriamwebster.com. Encyclopedia Britannica. MerriamWebster. Last Accessed 8/7/2018. http://www.merriamwebster.com/dictionary/interior angle. Buy the book
 Casey, John, LL.D., F.R.S.. The First Six Books of the Elements of Euclid. pp 8,2829. Translated by Casey, John, LL.D. F.R.S.. www.archive.org. Hodges, Figgis & Co.. 1890. Last Accessed 8/7/2018. http://www.archive.org/stream/firstsixbooksofe00caseuoft#page/8/mode/1up/search/interior. Buy the book
 Williams, Cora Lenore. Syllabus of Plane Geometry. pg 14. www.archive.org. Standard Press. 1905. Last Accessed 8/7/2018. http://www.archive.org/stream/syllabusofplaneg00willrich#page/14/mode/1up/search/interior. Buy the book
 Noetling, William. Elements of Constructive Geometry, Inductively Presented. pg 13. www.archive.org. Silver, Burdett & Company. 1897. Last Accessed 8/7/2018. http://www.archive.org/stream/elementsofconstr00noetrich#page/13/mode/1up/search/interior. Buy the book
More Information
 McAdams, David E.. Polygon. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 3/12/2009. https://www.allmathwords.org/en/p/polygon.html.
Cite this article as:
McAdams, David E. Interior Angle. 4/23/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. https://www.allmathwords.org/en/i/interiorangle.html.
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Revision History
4/23/2019: Updated equations and expressions to new format. (
McAdams, David E.)
12/21/2018: Reviewed and corrected IPA pronunication. (
McAdams, David E.)
8/6/2018: Removed broken links, updated license, implemented new markup, implemented new Geogebra protocol. (
McAdams, David E.)
2/18/2010: Added "References". (
McAdams, David E.)
8/12/2008: Added definition 2, added dictionary.com to 'More Information' (
McAdams, David E.)
6/7/2008: Corrected spelling. (
McAdams, David E.)
6/4/2008: Initial version. (
McAdams, David E.)