In the applet below you can experiment with the locus definition of an ellipse: the locus of points, P, such that the sum of the distances from two fixed points, called the foci , is constant.
Drag E below and observe the path that F and G follow. After points have been traced, clicking the red X in the bottom right corner will erase the traced points.
The sketches on this page were created with JavaSketchpadTM software that lets you interact with sketches from The Geometer's Sketchpad®, in a Java-enabled web browser.
JavaSketchpadTM ©2000 by KCP Technologies, Inc. Used under license.
JavaSketchpad is a trademark of KCP Technologies, Inc.