The purpose of this note is to present two or three gadgets which may be used to demonstrate the Pythagorean Theorem. The models may easily be made of heavy paper, cardboard, or light weight plastics. Of course, more elaborate ones, large and small sized, can be constructed of wood, metal, wallboard, heavy plastics, etc. The first of these demonstrators is based upon the geometric figure suggested by Chou-pei, China, about 1100 B.C. Chou-pei gave no proof. He merely drew the figure and uttered not one murmur of explanation. The second model is based upon the well known figure usually accredited to Bhaskara. It has a novel attachment which renders the demonstration dependent only upon pulling a string, or turning a crank, or winding a key, whichever the maker has available. The proof for the third demonstrator is new, but has a slight similarity to proofs 19 and 23, pp. 112-114 of reference 9. The fourth treats the old familiar special case of the 3-4-5 triangle. It is interesting to see how the two small squares can be folded together to form the square on the hypotenuse. These gadgets were selected because the proofs can be given by using the gadget figures themselves. in presenting this topic there are two questions which seem to bear directly on the subject. The first question: Demonstrative Geometry. There are those among us who advocate a demonstration of any kind (including tap dances in 2/4, 3/4, 4/4, or 6/8 time) even at the expense of systematic proofs. Others in the mathematics camp frown and flinch at the slightest mention of any sort of demonstration. The writer, evading an answer to this issue, believes that a great mistake is made if a person devours nothing but demonstrations during his opportunity to learn geometry. On the other hand, if a model makes the problem clearer and more understandable, then the relatively small amount of time devoted to the demonstration is, perhaps, well spent. If one of these gadgets helps anyone to understand the meaning of the Pythagorean Theorem, if one helps him to get the real picture of the problem, and, if it helps him to outline and render a logical proof of this important and interesting proposition then the writer shall have no qualms about the time spent in designing these gadgets in answer to an inquiry for just one such tool.
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