An interactive applet and associated web page that demonstrate the apothem of a regular polygon. The applet shows a regular polygon where the user can alter the number of sides and resize it by dragging any vertex. At all times, the apothem (line from center to a midpoint of a side) is drawn and it's length shown.

The text on the page shows two formulae for calculating the apothem, depending on what you are give to start.

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.