Search
Google ClassroomGoogle Classroom
GeoGebraGeoGebra Lesson
GeoGebra
  • Home
  • Resources
  • Profile
  • Classroom
  • App Downloads

Sum of angles of a triangle: the proof

Author:Ilya V. Schurov
Topic:Angles
Very classical picture. Based in part on the work by Andy Talmadge.

New Resources

  • Pythagorean Theorem: Extension Exercises
  • Congruent Sides & Angles in △s: Exploration
  • Writing and Graphing Proportional Relationships (k>0)
  • Midpoint Theorem (V2): Integer Solutions
  • Slope Illustrator (2)

Discover Resources

  • KelleherS_Rotation.ggb
  • Describe the Transformation page 1
  • Meeting Mr. Worldwide
  • Triangle Centers Adjustable
  • Binary order

Discover Topics

  • Function Graph
  • LCM and GCD
  • Boxplot
  • Cube
  • Step Functions
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®