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Homework Help: Vector arc length problem

  1. Sep 30, 2009 #1
    1. The problem statement, all variables and given/known data
    Find Arc Length:
    r(t)=t^3 i+tj+(1/2)[tex]\sqrt{6}[/tex]t^2k 1[tex]\leq[/tex]t[tex]\leq[/tex]3


    2. Relevant equations
    The arc length formula:
    integrate: sqrt((dx/dt)^2+(dy/dt)^2+(dz/dt)^2) dt


    3. The attempt at a solution
    I can find the derivative and plug into the formula, it's just the simplification that is absolutely stumping me. I haven't done this for a long time, which is always why my TeX is horribly put together.

    Any help is greatly appreciated. I've gotten to here so far:

    [tex]\int_1^3 \! \sqrt{9t^4+1+6t^2} \, dt.[/tex]
     
  2. jcsd
  3. Sep 30, 2009 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    The expression under the square root is a perfect square. Factor it!
     
  4. Oct 1, 2009 #3
    Thank you. I'm sorry for the nonsensical post, I guess I was way too tired to not have that jump out at me.

    Again, thank you.
     
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