# Vertical Angles

Pronunciation: /ˈvɜr.tɪ.kəl ˈæŋ.gəlz/ Explain

 Click on the blue points and drag them to change the figure. Manipulative 1 - Vertical Angles Created with GeoGebra.

Manipulative 1: Vertical angles.

Vertical angles are a pair of angles formed by intersecting lines that are opposite each other. Each pair of intersecting lines forms four angles and two pair of vertical angles.

### Vertical Angle Congruence Theorem

The Vertical Angle Congruence Theorem shows that vertical angles are always congruent.

StepDescriptionJustification
1Angles 1 and 2 are supplementary. The definition of supplementary.
2Angles 2 and 3 are supplementary. The definition of supplementary angles.
3Angles 1 and 3 are congruent. Q.E.D. The Supplementary Angle Congruence Theorem
Table 1: Proof of the Vertical Angle Congruence Theorem

1. McAdams, David E.. All Math Words Dictionary, vertical angles. 2nd Classroom edition 20150108-4799968. pg 189. Life is a Story Problem LLC. January 8, 2015. Buy the book

McAdams, David E. Vertical Angles. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/v/verticalangles.html.

### Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)