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Homework Help: Derivatives halp

  1. Nov 4, 2007 #1
    1. The problem statement, all variables and given/known data
    find the derivative using the appropriate rules

    y=sin(cos(sinx))


    3. The attempt at a solution

    d/dx[sin(cos(sinx))] = [cos(cos(sinx))] * [-sin(sinx)] =

    -cos(cos(sinx))(sin(sinx))

    Is that right?

    It doesn't feel right.
     
  2. jcsd
  3. Nov 4, 2007 #2

    rock.freak667

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    Try making an extended chain rule...let t=sinx and then u=cost ...and then differentiate and use the chain rule
     
  4. Nov 4, 2007 #3
    you're very close!!! 1 more angle
     
  5. Nov 4, 2007 #4
    is the first factor done? and -sin(sinx) needs more?
     
  6. Nov 4, 2007 #5
    something like this: y= sinu ; u=cos(t) ; t=sinx

    d/du[y] * d/dt * d/dx[t] ?
     
    Last edited: Nov 4, 2007
  7. Nov 4, 2007 #6
    = cosu * (-sint) * cosx =

    -sin(sinx)*cos(cos(sinx))*cosx ??
     
  8. Nov 4, 2007 #7

    rock.freak667

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    well the chain rule is correct...so I would assume that it is correct
     
  9. Nov 4, 2007 #8
    It wouldn't be uncommon for me to apply a rule incorrectly.
     
  10. Nov 5, 2007 #9

    rock.freak667

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    Well it is correct
     
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