# Box of primes over l V X a l ^2

1. Oct 3, 2011

### maysenator

"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. Oct 3, 2011

### maysenator

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