An interactive applet and associated web page that demonstrate equiangular triangles (all interiro angles congruent). The applet presents an equiangular triangle where the user can drag any vertex. As the vertex is dragged, the others move automatically to keep the triangle equiangular. The angles and side lengths are updated continuously to show that the all interior angles are always congruent.

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.