# Dihedral Angle

Pronunciation: /daɪˈhi.drəl ˈæŋ.gəl/ Explain

 Click on the blue points and drag them to change the figure. Why do you think that the dihedral angle between two planes is never greater than 180 degrees? Manipulative 1 - Dihedral Angle Created with GeoGebra.

A dihedral angle is the angle formed by two intersecting planes. The Intersecting Planes Postulate tells us that intersecting planes form a line. Take a line in each plane that is perpendicular to the line of intersection. The two lines must intersect. The dihedral angle of the planes is the angle between the two lines.

### References

1. McAdams, David E.. All Math Words Dictionary, dihedral angle. 2nd Classroom edition 20150108-4799968. pg 60. Life is a Story Problem LLC. January 8, 2015. Buy the book

McAdams, David E. Dihedral Angle. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/d/dihedralangle.html.

### Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
5/7/2008: Initial version. (McAdams, David E.)

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