Dr. H. Vogel - Zentrum Mathematik - Technische Universität München

1. Illustration of well known geometry facts using
the move mode and the animation mode

We consider the pedal triangle PQR of the triangle ABC with respect to the point X. We ask for the locus of X while the pedal triangle degenerates into a line of collinear points [PQR]. This straight line is called the "WALLACE-line of the triangle ABC with respect to the point X". This line is also called SIMSON-line.

Bitte schalten Sie Java ein, um eine Cinderella-Konstruktion zu sehen.
Figure 1
Bitte schalten Sie Java ein, um eine Cinderella-Konstruktion zu sehen.
Figure 2

Using the move mode in figure 1 we see, that the solution is the circumcircle u of the triangle ABC. This is an example for the useful tool "Bind a Point on a Line", which will be available in version 2 of CINDERELLA. Figure 2 shows the solution in the animation mode.

Hint: In figure 1 and all following figures without animations you can move the red colored points like [Red point] by mouse-clicking.

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