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Help: Lorentz transform for angles

  1. May 7, 2005 #1
    Hi everybody,
    I would need to find the lorentz transform for angles from primed to unprimed system. Could someone help fast?

    Thanks a bunch, best,

  2. jcsd
  3. May 7, 2005 #2


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    Consider a right-triangle with legs:
    x along the direction of motion and
    y along a perpendicular direction.
    Define tan (theta)=y/x in the frame of that triangle.
    How do the legs transform?
  4. May 7, 2005 #3
    Thanks, yes, that's what I do, but there are worked out formulae, with
    sin(theta) as a function of tan(theta'/2) or something...
    That's what I was looking for.

    Thanks anyway, best,

  5. May 7, 2005 #4

    If you can't write the formula from the help that robphy gave, you don't deserve your username! ;-)
  6. May 7, 2005 #5
    Dear all,
    is this a place to help or to show off?
    tan(theta)=(1/gamma)*tan(theta'), thanks a lot, I can see that, professors...
    But there is a set of worked out, simple formulae also for the transformation of sinuses, cosinuses, etc. Of course I can do any calculation without, but they would be useful to simplify my life...

    Best, anyway,

  7. May 7, 2005 #6


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    What use would it be to you knowing how the other "trigonometrical functions" would transform under a SLT...?You're interested in knowing how [itex]\theta[/itex] transforms,not [itex] \tan\theta,\sin\theta,\cos\theta,\arcsin\theta,\arccos\theta,...[/itex].

  8. May 8, 2005 #7
    In order to simplify calculations...

    Best wishes,

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