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Root 2 irrationality proof (geometric)

  1. Sep 29, 2013 #1
    I was looking over this proof and I have some questions:

    http://jeremykun.com/2011/08/14/the-square-root-of-2-is-irrational-geometric-proof/

    Second paragraph, what does "swinging a b-leg to the hypotunese" mean? Also, where did the arc come from, I really don't understand

    also, the last part ## \dfrac{2b-a}{a-b} ## how does this lead to a contradiction (i.e. how is 2b-a and a-b smaller than a and b?

    really don't understand the proof overall, if someone could walk me through it or give me some pointers it'd really help thank you
     
  2. jcsd
  3. Sep 29, 2013 #2

    tiny-tim

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    hi phospho! :smile:
    it's a really stupid way of saying "draw an arc of a circle of radius b from R to the hypotenuse" :redface:
    2b - a = b + (b -a), which is obviously < b :wink:

    (and a - b < a)
     
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