Geometry Lesson 2.3: Parallel Lines and Triangle Angle Sums

This lesson covers the triangle angle sum and the triangle exterior angle sum. We prove the triangle angle sum using a flow proof, and we work problems involving finding missing angles of given triangles.

[alexandraserrano]

Thank you for this!! I really needed this!

[ducko.]

5:22 30+135+25=190 not 180, the last angle you measured was 15, not 25, thought id let you know :)