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Homework Help: Arc legth of curve C in first octant

  1. Mar 11, 2009 #1
    Let C be the curve obtained by intersecting the sphere x^2 + y^2 + z^2 = a^2 with the surface root(x^2 + y^2)cosh(arctan(y/x))=a.
    Find the length in the first octant that joins the points A (a,0,0) and B(x,y,z).

    Im not sure what to do. Should i change it into different types of coordinates?
  2. jcsd
  3. Mar 11, 2009 #2


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    Welcome to PF!

    Hi moneyjane! Welcome to PF! :smile:

    (have a square-root: √ and a theta: θ and try using the X2 tag just above the Reply box :wink:)
    Yup … looks like it would be a lot simpler if you changed to cylindrical coordinates (r,z,θ) with r = √(x2+ y2) and tanθ = y/x :wink:
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