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Homework Help: Differential Geometry

  1. Nov 17, 2013 #1
    1. The problem statement, all variables and given/known data
    Using the curve [itex]\vec{a}[/itex](u,v)= (u,v,uv) for all (u,v) ε R^2

    Find the matrix for d[itex]\vec{N}[/itex] in the basis of {[itex]\vec{a}[/itex][itex]_{u}[/itex],[itex]\vec{a}[/itex][itex]_{v}[/itex]}
    2. Relevant equations
    Well first off i found the partial derivatives
    [itex]\vec{a}[/itex][itex]_{u}[/itex] which is 1,0,v, while [itex]\vec{a}[/itex][itex]_{v}[/itex] is 0,1,u
    Then using those i found the normal vector which i calculated as [itex]1/\sqrt{v^{2}+u^{2}+1}[/itex] (-v,-u,1)

    3. The attempt at a solutionNow this is where i get lost. Our book does not explain this very well at all. It just shows going fron N to dN with no explanation. I tried using the jacobian matrix to calculate the derivative but I'm not sure if this is the right approach. Most of the examples don't have a matrix from so i Know i'm doing something wrong.

    The problem is a set from kbw0RwT.png for reference. I need dN to move on to find the second fundamental forms and so forth
  2. jcsd
  3. Nov 17, 2013 #2
    Actually could i bring out the 1/sq u^2... out of the jacobian matrix then use the matrix to find the vector or no? so only the -v,-u,1 would be getting partially derived in the matrix?
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