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Homework Help: Box of primes over l V X a l ^2

  1. Oct 3, 2011 #1
    "box of primes" over l V X a l ^2

    1. The problem statement, all variables and given/known data

    Find B, and t for these space curves (t = torsion)

    r(t) = (3sint)i + (3cost)j + 4tk

    2. Relevant equations

    Ok, so in my textbook i have two different equations to find the answer to this.

    the "box of primes" over l V X a l ^2 method which im NOT ALLOWED to use.

    i am supposed to get torsion using t = -dB/ds N

    When i use the latter, i keep getting -4, but with the long definition i can get -4/25 (the right answer)

    3. The attempt at a solution

    I calculate -dB/ds as (4sinti + 4costj) and N (-sint - cost)

    im a little confused and getting lost in all the different definitions of everything!!!

    anyone care to shed a little light thanks in advance!!
  2. jcsd
  3. Oct 3, 2011 #2
    Re: Torsion

    i figured it out, only a small mistake

    for anyone who may encounter this exact scenario

    i was forgetting dt/ds as 1/lvl where as ds/dt is mag v

    small dumb error
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