Alternate Angles

The diagram shows two parallel lines and a transversal.
Move the point B.
What do you notice about the two marked angles?

These angles are called alternate or Z angles as the angles are on alternate sides of the transversal.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Can you explain why these two angles are equal, using the previous results?

Click on the Show object button to see another set of alternate angles.

Created with GeoGebra