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

  • bewijs stelling van Pythagoras
  • Trefoil Knot
  • Untitled
  • Average Distance
  • Triangle Flexer

Discover Resources

  • Square Dissection Puzzle Dilemma
  • Accuracy and Precision
  • pplot4
  • AB+2CD
  • Marino_Period2_PropertiesOfTransformations
  • cone22

Discover Topics

  • Bar Chart or Bar Graph
  • Inequalities
  • Geometric Mean
  • Rhombus
  • Circle
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

© 2025 GeoGebra®