An interactive applet and associated web page that demonstrate opposite rays. The applet shows two rays with a common endpoint and can be dragged with the mouse. If the rays are in a line, the message "Opposite rays" appears. A detent makes it easier to get them perfectly aligned.

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.