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Homework Help: Angle between vectors help

  1. Sep 26, 2007 #1
    1. The problem statement, all variables and given/known data

    The figure shows a mast and parts of the equipments of a sailboat. The elements CD and EF belongs to the same plane, CD has 7.5m of lenght and has an angle of 45º with a vertical line that passes by C. When [tex]\theta[/tex] = 15º the tension in the rope AB is 230N.

    http://img128.imageshack.us/img128/8149/problemas3.th.jpg [Broken]

    a) find the angle between the ropes AB and BD

    2. Relevant equations

    ABcos([tex]\theta[/tex]) = A.B

    Where bold letters represent vectors.

    3. The attempt at a solution

    I started by finding the coordinates of points A, B and D.

    A = (0.5,0,-3)
    B = (x, 22, 0)
    D = ?

    I get lost finding the x coordinate for B and the coordinate of D. With these coordinates I can find the vectors that I need to apply the equation above by doing the following:

    AB = (x - 0.5)i + (22-0)j + (0 + 3)k

    Any ideas?

    Last edited by a moderator: May 3, 2017
  2. jcsd
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