Search
GeoGebra
  • Home
  • Resources
  • Profile
  • Classroom
  • App Downloads

Lesson 86. Properties of Parallel Lines

Author:Norm Prokup

T6-criterion for parallel lines

[bgcolor=orange] If two lines are intersected by a third line, and alternate interior (or exterior) angles are equal, then the original two lines are parallel. [/bgcolor]

New Resources

  • Rolling a Square
  • 巧算長方形周界
  • Nikmati Keunggulan Di Bandar Judi Terpercaya
  • Parallel lines, Transversals and Segments
  • The Coordinate Plane (Cartesian Plane)

Discover Resources

  • Fit Exponential Growth Function
  • Parallelogram Properties
  • parabula10
  • Untitled
  • parabel_streckung

Discover Topics

  • Median Line
  • Ellipse
  • Circle
  • Terms
  • Solids or 3D Shapes
AboutPartnersHelp Center
Terms of ServicePrivacyLicense
Graphing CalculatorCalculator SuiteMath Resources

Download our apps here:

Download_on_the_App_Store_Badge_US-UK_RGB_blk_4SVG_092917

© 2026 GeoGebra®