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A question in space geometry

  1. Mar 17, 2004 #1
    Ok, you take a rectangular and fold it along one of its diagonal, so that the two planes are perpendicular to each other.

    Using [tex]a[/tex] and [tex]b[/tex], what is the distance between the points A and B ([tex]d[/tex])?

    My anwer is:
    [tex]d = \sqrt{a^2 + b^2 - \frac{2a^2b^2}{a^2 + b^2}} = \sqrt{\frac{a^4 + b^4}{a^2 + b^2}}[/tex]
    But I doubt that it's actually correct. :)

    Attached Files:

    Last edited: Mar 17, 2004
  2. jcsd
  3. Mar 17, 2004 #2
    By the way, this is how I solved it (see attachment). I found x and f with Pythagoras, and using f I found y with the cosine law (the extended Pythagoras thing :wink:). And from there I just used x and y to find d with Pythagoras.

    So is this correct, and is there an easier way to do this?

    Attached Files:

  4. Mar 20, 2004 #3


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    Homework Helper

    I got the same answer so I am sure it is correct. The only slight difference in what I did was I used the two perpendicular heights and the distance between them.
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