Diagrammatic Proof of Pythagoras Theorem

Independence of Triangle Dimensions

  1. First phase: right-hand copy of left-hand picture has the triangles rotated and then slid into position. Triangles with the same color in the left and right diagrams are counterparts in the sense of Barwise and Etchemendy. The blue areas in both diagrams therefore have the same measure.
  2. Second phase: shows the continuity of the correspondence; as left triangle dimensions change, the identical change appears on the right. Hence, the proof is independent of relative side dimensions of the triangles.

I am afraid this Java applet is not one of the most elegant that I have written. One day I will find the time to go back and clean it up, providing you with slider bars to control (and pause!) the animation as you please.

Click here to Re-do the Animation

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