The applet shows a triangle which the user can resize by dragging any of its vertices. It shows the three perpendicular bisectors of the sides and the point where they intersect - the circumcenter. These track the changes in the triangle in real time. It shows that the circumcenter may lie outside the triangle.

The associated web page describes the properties of the circumcenter and points out that it the center of the triangle's circumcircle.

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.