Texas Instruments
Texas Instruments: Angles Formed by Two Intersecting Lines
Students will investigate the properties of angles formed by intersecting lines. They examine the definition of adjacent angles, supplementary angles, and vertical angles and learn about two important geometric theorems dealing with...
Oswego City School District
Regents Exam Prep Center: Geometry Vocabulary Resources
A list of geometry definitions and a matching activity.
Math Open Reference
Math Open Reference: Vertical
Learn about vertical lines with this handy reference guide. Provides a detailed definition and examples that enhance further explanation. Includes links to related topics.