Thales of Miletus is often considered the first great Greek mathematician. He seems to be the beneficiary of history's first attribution: "Hey, this is Thales' theorem." See a biography at MacTutor: [url]http://www-history.mcs.st-and.ac.uk/Mathematicians/Thales.html[/url][br][br]What he noticed and proved concerned a connection between right triangles and circles. What do you notice?[br][br]Why is it true?[br][br]Could you prove it's always true? Thales' proof seems to have used that the sum of the angle measures in a triangle are equal to two right angles. (What we call 180 degrees, nowadays.)

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