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Homework Help: Directional Derivative question. Calculus III/2-variable.

  1. Oct 31, 2012 #1
    1. The problem statement, all variables and given/known data

    Let f(x,y,z)=sin(xy+z) and P=(0,-1, pi), Calculate Duf(P) where u is a unit vector making an angle 30°
    =θ with dFp?
    2. Relevant equations
    This is a two variable problem, where partials are necessary in order to find the gradient formula to get <dFP>. To take the Directional Derivative, from what I know, you require the following equation... <dFP>dot<U>/||u||.


    3. The attempt at a solution
    from the following I calculated the gradient equation to be
    <ycos(xy+z),xcos(xy+z),cos(xy+z)>

    with the given gradient equation, I get dFP as <1,0,-1>.

    What I cannot figure out is how to get the coordinates for the U vector.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
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