Obtuse Triangle

Pronunciation: /əbˈtus ˈtraɪˌæŋ gəl/ ?

An obtuse triangle is a triangle where one of the angles is an obtuse angle. [1][2] An obtuse angle is an angle with a measure of more than 90° (π radians). See figure 1. Since all triangles that do not have a right angle are scalene triangles, all obtuse triangles are obtuse scalene triangles.

Obtuse Scalene Triangle
Figure 1: Obtuse scalene triangle

References

  1. Casey, John, LL.D., F.R.S.. The First Six Books of the Elements of Euclid, pg 8. Translated by 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/obtuse.
  2. obtuse triangle. merriam-webster.com. Encyclopedia Britannica. (Accessed: 2009-12-21). http://www.merriam-webster.com/dictionary/obtuse triangle.

More Information

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

Printed Resources

Cite this article as:


Obtuse Triangle. 2009-12-21. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/o/obtusetriangle.html.

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Revision History


2009-12-21: Added "References" (McAdams, David.)
2008-08-26: Revised references to 'scalene' and revised 'More Information' (McAdams, David.)
2007-07-12: Initial version (McAdams, David.)

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