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Homework Help: Three Forces: Equilibrium

  1. Apr 19, 2009 #1
    1. The problem statement, all variables and given/known data
    Forces of 5N, 7N, and 8N are applied to an object, calculate the angle between the lines of action of the 5N and 7N forces.

    2. Relevant equations
    Sin, cos, and tan relationships

    3. The attempt at a solution
    I know that you have to use components, but I don't see how to do this without knowing at least one angle.
  2. jcsd
  3. Apr 19, 2009 #2


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    Homework Helper

    According the cosine rule
    a^2 = b^2 + c^2 - 2bc*cosθ. In the problem a, b and c is given. Find θ.
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