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Homework Help: Vector and components problem

  1. Sep 3, 2006 #1
    I'm suppose to find the ordered pair (x,z) for components of the vector R(AB), which I am suppose to be able to find by R(AB) = R(B) - R(A).

    http://server6.theimagehosting.com/image.php?img=phytest.jpg

    So far, I solved for the components of the vector of B, and the vector of A.

    Vector A:
    cos 40 = x/360; x = 276
    sin 40 degrees = y/360; y = 231
    = (276, 231)

    Vector B:
    I guess to use sin, cos, tan I need a right angle. So I do the bottom of B to do it. (123+40=163; 180-163=17 degrees)
    cos 17 = x/880; x = 842
    sin 17 = y/880; y = 257
    = (842, 257)

    Vector B - Vector A = (842, 257) - (276, 231) = (566, 26)

    Which is wrong. What am I doing wrong? Should I be doing Vector B a different way? Or did I do the entire thing wrong?
     
  2. jcsd
  3. Sep 3, 2006 #2

    Kurdt

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    What you've forgotten to do is to take into account that the B x coordinate should be negative because you have crossed the perpendicular to the origin.

    B = (-842,257)

    easy mistake to make.
     
  4. Sep 3, 2006 #3
    Well, that makes it:
    (-842, 257) - (276, 231) = (-1118, 26)

    Unfortunately it's still wrong, I guess I'll have to think of something else.
     
  5. Sep 4, 2006 #4

    Kurdt

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    Could you clarify exactly what vector they want you to find or post the answer so I can work it out. Are you sure you're supposed to only subtract a from b?
     
  6. Oct 9, 2011 #5
    The answer is (1100, 26). Your answer was off due a slight rounding error.
     
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