William Dunham showed me this elegant symmetric proof of Heron's formula by Bernard Oliver http://johnng.inscyber.net/proof-without-words-heron.pdf …pic.twitter.com/A4BQqzuMN0
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@stevenstrogatz Then Heron follows from "The sum of the squares on the sides of a parallelogram equals the sum of the diagonal squares."
@MathPrinceps Thanks for all the interesting comments and tips!
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