Calc 3 question (binormal, normal vectors)

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SUMMARY

The discussion centers on the calculation of binormal and normal vectors in Calculus 3, specifically using the formulas B = T x N, B = (R'(t) x R''(t)) / | R'(t) x R''(t) |, and T = R'(t) / | R'(t) |. A participant inquires if the normal vector N can be expressed as N = R''(t) / |R''(t)|, which is clarified as incorrect. The correct formulation for the normal vector is N = T' / |T'|, emphasizing that this is not equivalent to R''(t) / |R''(t)| when the magnitude of T is not constant.

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jaejoon89
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Hi, this is a calc 3 question. I know the binormal is given by

B = T x N

where
Binormal vector, B
Tangent vector, T
Normal vector, N

Also,
B = (R'(t) x R''(t)) / | R'(t) x R''(t) |
T = R'(t) / | R'(t) |

Does that mean
N = R''(t) / |R''(t)|?
 
Last edited:
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jaejoon89 said:
Hi, this is a calc 3 question. I know the binormal is given by

B = T x N

where
Binormal vector, B
Tangent vector, T
Normal vector, N

Also,
B = (R'(t) x R''(t)) / | R'(t) x R''(t) |
T = R'(t) / | R'(t) |

Does that mean
N = R''(t) / |R''(t)|?
No.
[tex]\vec{N}= \frac{\vec{T}'}{|\vec{T}'|}[/itex]<br /> Which is NOT the same as <br /> R"/|R"|<br /> if |T| is not a constant.[/tex]
 

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