An interactive applet and associated web page that demonstrate the corresponding angles that are formed where a transversal crosses two lines. The applets cycles through the four possible pairs of angles when in animation mode. By dragging the three lines, it can be seen that the angle pairs are congruent only when the lines are parallel. When not in animated mode, there is a button that cycles through each the four pairs of angles.

The text on the page discusses the properties of the pairs of corresponding angles both in the parallel and non-parallel cases.

Applet can be enlarged to full screen size for use with a classroom projector. After use in the classroom, student can access it again from any web browser at home or in the library with no login required.

This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.