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Homework Help: Coordinate geometry

  1. Dec 31, 2011 #1
    1. The problem statement, all variables and given/known data

    Given that P,Q and R lie on the hyperbola xy=c2, prove that if PQ and PR inclined equally to the coordinate axes, then QR passes through O.

    2. Relevant equations

    3. The attempt at a solution

    I don't understand what does ''PQ and PR are inclined equally to the coordinate axes'' means.. can anyone explain?
  2. jcsd
  3. Jan 1, 2012 #2


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    Homework Helper

    This means that their slopes are opposites, I believe. In other words, if the slope of PQ is m, then the slope of PR is -m.
  4. Jan 3, 2012 #3
    I'd have to say, it sounds to me like the slope along x = slope along y, it's symmetric under swapping x and y
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