regular smooth curve - Penn Math
regular smooth curve - Penn Math
regular smooth curve - Penn Math
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Problem. To get a Frenet frame along a <strong>curve</strong> in R 3 , one<br />
needs to assume that the curvature �(s) never vanishes.<br />
Without this hypothesis, one can still prove that<br />
vol �-tube = (length of <strong>curve</strong>) (area of �-disk) .<br />
(a) Let T(s) , A(s) , B(s) be an ON frame along our<br />
<strong>curve</strong> x(s) . Show that the Frenet eqns are replaced by<br />
T'(s) = �(s) A(s) + �(s) B(s)<br />
A'(s) = � �(s) T(s) + �(s) B(s)<br />
B'(s) = � �(s) T(s) � �(s) A(s) .<br />
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