The Pythagorean Theorem states that for a right triangle with legs of length a and b and hypotenuse of length c, a2 + b2 = c2 Look at this diagram, a + b on a side.

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B E H O L D !

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QED. Ph34r my l33t 930m37ry ski11z.

OK, so it isn't really a one-word proof; most of the proof is embedded in the diagrams. Observe that, by the binomial theorem, a^2 + b^2 + 2ab = (a + b)^2 (first diagram); manipulating the four triangles produces (a + b)^2 - 2ab = c^2.

Gorgonzola observes: "If a picture is worth a thousand words, this is a 2001 word proof."

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