Investigating Mathematics with GeoGebra

Henrico County Public Schools

What are the angle relationships?

READ the instructions on the right and INTERACT with the GeoGebra applet below.
Click on the reset icon icon to reset the diagram.

Sorry, the GeoGebra Applet could not be started. Please install Java 1.4 (or later) to use this page.

Investigation Steps

 Step 1 Close 
  1. Parallel lines AB and CD were constructed and intersected by another line EF.

  2. Locate the corresponding ∠CHF and ∠AGH.

  3. Why are these angles called corresponding angles?

  4. What do you notice about their measures?

  5. Move points A, C, & F to confirm your findings.
 Step 2 Close 
  1. Locate the alternate interior angles ∠GHD and ∠AGH.

  2. Why are these angles called alternate interior angles?

  3. What do you notice about their measures?

  4. Move points A, C, & F to confirm your findings.
 Step 3 Close 
  1. Locate the alternate exterior angles ∠CHF and ∠EGB.

  2. Why are these angles called alternate exterior angles?

  3. What do you notice about their measures?

  4. Move points A, C, & F to confirm your findings.
 Step 4 Close 
  1. Locate the adjacent angles ∠CHF and ∠CHG.

  2. Why are these angles called adjacent angles?

  3. What do you notice about their measures?

  4. Move points A, C, & F to confirm your findings.

 Check ConjecturesClose 
  1. Parallel lines cut by a transversal have corresponding angles equal, alternate interior angles equal, and alternate exterior angles equal.

  2. Parallel lines cut by a transversal have adjacent angles supplementary, and interior angles on the same side of the transversal supplementary.