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Homework Help: Magnitude and Direction of Force

  1. Nov 2, 2008 #1
    1. The problem statement, all variables and given/known data

    http://img243.imageshack.us/my.php?image=61581222vi0.jpg
    http://xs433.xs.to/xs433/08440/untitled601.jpg [Broken]

    I need to find the direction and the magnitude of F3 given only the figure and the resultant force of the 3 vectors =20 lb, plus F3 being the smallest force between all of them.

    3. The attempt at a solution

    Tried Rx and Ry and squaring them but I have 3 unknows in 1 solution...

    any ideas?
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Nov 2, 2008 #2

    tiny-tim

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    Welcome to PF!

    Hi chadovP! Welcome to PF! :smile:

    (have a theta: θ :wink:)

    I don't get it :confused:

    the only two unknowns are F3 and θ …

    what unknowns did you have? :smile:
     
  4. Nov 2, 2008 #3
    yes but there are sin θ and cos θ which makes the equation very complicated.
     
  5. Nov 2, 2008 #4

    tiny-tim

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    ah!

    but that's still only one unknown!

    Hint: square, and add. :wink:
     
  6. Nov 2, 2008 #5
    2 unknows mate! F3 and the angle...
    so i have f3 sqaured and the angle in one equation and that the part i am not getting...
     
  7. Nov 2, 2008 #6

    tiny-tim

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    square, and add! :rolleyes:
     
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