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Homework Help: Magnitude and direction

  1. Jan 26, 2004 #1
    My problem is to determine the magnitude and direction of the resultant force FR=F1+F2 and it's direction, measured counterclockwise from the positive x direction.

    f1=250 lb @ 60 degrees from x
    f2= 375 lb @ -45 degrees from x

    Ok I got the magnitude by doing this:
    (360-2(255))/2=-75 degrees

    fr=sqroot of (250^2+375^2-2(250)(375)cos(75)
    fr=393.188~ 393

    then I got the angle by this:
    375/sin x = 393.188/sin 75
    how do i get the resultant angle, what do I need to add to the 67 degrees?

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  2. jcsd
  3. Jan 26, 2004 #2
    U have ur replies at Homework Section where the above pro should be
  4. Jan 26, 2004 #3


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    Science Advisor

    The easiest way to do it is by computing the x and y components of F1 and F2, add them respectively to get the x and y components of FR, and compute the magnitude and directions from these. It is a simple analytic geometry problem.
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