Finding Curvature and Torsion: Derivatives and Unit Vectors Explained

[dimpledur]

Homework Statement

http://www.mathhelpforum.com/math-help/attachments/f6/22423d1317129472-curvature-torsion-untitled.png

The Attempt at a Solution

What I did was I calculated the unit vector for dN/ds={.21i+0.91j-0.42k}/ sqrt(.21^2+.91^2+0.42^2)=.205i+0.889j-.4102k


then, I took a derivative of N

since N=BxT,

dN/ds=(dB/ds)xT+Bx(dT/ds)
then taking T and doing dot product on both sides:
T⋅(dN/ds)=T⋅(dB/ds)xT+Bx(dT/ds) which simplifies to:
T⋅(dN/ds)=dB/ds
T⋅(dN/ds)=-τN

From here I have no clue what I should be doing..

Any suggestions will be greatly appreciated

 

[dimpledur]

nvm figured it out