Statics Question: Finding resultant force and orientation

  1. [​IMG]

    Determine the magnitude of the resultant force FR. Assume that F1 = 230 and F2 = 395
    Express your answer to three significant figures and include the appropriate units.

    Determine the direction of the resultant force FR , measured counterclockwise from the positive x axis.

    I got the magnitude as 402lb which is correct, but I am having trouble finding the direction of the force.

    I have the following work below


    So I get [itex]\phi[/itex]=71.6 degrees

    Now the first quadrant has an angle from F1 to the x axis that measures at 60 degrees. What I did was 71.6-60 degrees = 11.6 degrees and said that was the angle of the resultant force, but this answer is wrong.

    Can anyone explain how to find the angle? Should I be subtracting 360 from 11.6 degrees instead since it wants the position counterclockwise?
  2. jcsd
  3. SteamKing

    SteamKing 10,929
    Staff Emeritus
    Science Advisor
    Homework Helper

    Why don't you find the components of F1 and F2 and add them to determine the resultant?
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