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Different perspectives

  1. Apr 12, 2003 #1
    The other day, I was looking at two intersecting straight lines. They were drawn from a certain angle so that they looked acute. But if you sort of changed the angle of your view (by turning the paper a bit to the side), it looked like, quite simply, a coordinate plane without a graph. So, since the two lines where perpendicular to each other, does it mean they are right angles? Even if they only look acute?
    My sister and I had quite a bit of a quarrel over this...and I wanted an answer that was more substantiated, or rather "standard" so that more people could agree. Okay, so bring it on...
     
  2. jcsd
  3. Apr 13, 2003 #2

    HallsofIvy

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    HallsofIvy

     
  4. Apr 13, 2003 #3
    uhh...that was my question.
    By definition, perpendicular angles are right angles right?

    or is the whole situation relative? (i personally don't believe so)
     
  5. Apr 14, 2003 #4
    I don't think I follow what you say completely. Angle is a relative quantity due to Lorentz Transformations, and the way space changes while travelling at different speeds. But yeah, I don't think that was quite what you were asking.
     
  6. Apr 14, 2003 #5

    HallsofIvy

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    Oh, for God's sake don't bring relativity into it!


    Yes, "perpendicular" means "at right angles".

    Two lines are perpendicular if and only if they cross at right angles.
     
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