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Homework Help: Determine the magnitude of the resultant force

  1. May 15, 2010 #1
    The problem statement, all variables and given/known data
    If [tex]F_{B} = 5kN[/tex] and the resultant force acts along the positive u axis, determine the magnitude of the resultant force.


    The attempt at a solution

    [tex]F_{Rx} = F_{R}cos 30[/tex]

    [tex]F_{Ry} = F_{R}sin 30[/tex]

    [tex]F_{Rx} = 3 + 5cos\theta[/tex]

    [tex]F_{Ry} = 5sin\theta[/tex]

    Therefore, [tex]\frac{3 + 5cos\theta}{5sin\theta} = \sqrt{3}[/tex]

    Is this correct so far? I don't know how to isolate [tex]\theta[/tex]
    Last edited: May 15, 2010
  2. jcsd
  3. May 15, 2010 #2


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    Homework Helper

    What variable is the problem asking you to find?
  4. May 15, 2010 #3
    It is asking for the resultant force which acts along the u axis.
  5. May 15, 2010 #4
    That is right so you don't have to find [tex] \theta [/tex]
  6. May 15, 2010 #5
    Then how would I go about finding the resultant force? Using a combination of the equations I posted in my attempt?
  7. May 15, 2010 #6


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    Yep. I asked which variable the question was asking for for a reason; make sure you know which variable you need to find the value of and don't let it disappear when you combine the equations.
  8. May 15, 2010 #7
    But I still don't see how I can solve for the resultant force without first solving for theta. Am I missing something?
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