Box of primes over l V X a l ^2

[maysenator]

"box of primes" over l V X a l ^2

Homework Statement

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

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

Homework 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 I am 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)

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!

 

[maysenator]

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