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Cosine and Sine rules to get magnitude and direction of a resultant force

  1. Oct 20, 2009 #1
    Use the cosine and sine rules to determine the magnitude and direction of the resultant of a force of 11 kN acting at an angle of 50 degrees to the horizontal and a force of 6 kN acting at an angle of -30 degrees to the horizontal.

    helppp please
     
  2. jcsd
  3. Oct 20, 2009 #2

    danago

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    Gold Member

    What have you tried doing? Have you drawn a diagram of the situation -- Will make things much easier.
     
  4. Oct 20, 2009 #3
    No i haven't.
    Do you know how to find resultant forces with forces and angles from axises? because I have another problem like that and i have no idea how to do them
     
  5. Oct 20, 2009 #4

    danago

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    Well maybe draw one then :smile: At least then you actually have a triangle to apply the cosine and sine rules to.

    If you are given forces and angles relative to axes, you could again do the same thing and form a triangle to be solved with geometry, or perhaps easier would be to resolve each force into a horizontal and vertical component and add the components.
     
  6. Oct 9, 2010 #5
    Hi All
    to get magnitude of resultant use cosin rule R^2= X^2+Y^2 – 2XYcosβ
    to get the direction use sine rule = (Sin β /length of opposite line) = (sinθ/ length of opposite line)
     
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