Find the unit tangent vector T and the principal unit normal vector N. r(t) = (ln(cos t) + 4)i   + 7j  + (1 + t )k, -?/2 < t < ?/2

A. T = (-sin t)i  + (cos t)k; N = (-cos t)i  - (sin t)k
B. T = (sin t)i  - (cos t)k; N = (cos t)i  - (sin t)k;
C. T = (sin t)i  + (cos t)k; N = (cos t)i  - (sin t)k
D. T = (-sin t)i  + (cos t)k; N = (-cos t)i  + (sin t)k


Answer: A

Mathematics

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