Course Page for Rebecca McDowell

 

Parallel Lines and Transversals
Alternate Interior and Alternate Exterior Angles

This is designed to prove to students that alternate interior angles of two parallel lines cut by a transversal are equal. It is also designed to prove the same for alternate exterior angles of parallel lines cut by a transversal.

Below is a link to my Java Sketch. It can be used to explore alternate interior angles and alternate exterior angles.

Alternate Interior/Exterior Angles

 

Instructions:
Point B and Point D can either be manipulated by clicking and dragging them around the screen.
The top parallel line is j, the bottom parallel line is k, and the transversal line is l.

 

Questions:

  1. What do you notice about the angle measurements when you move Point D?
  2. What do you notice about the angle measurements when you move Point B?
  3. What conclusions can you draw from the commonalities and differences in the angle measure?