Consider the following vector function.

$r(t)=($:$7\sqrt[\phantom{2}]{2}t,e^{7t},e^{-7t}$:$)$

$($a$)$ Find the unit tangent and unit normal vectors $T(t)$ and $N(t).$

$T(t)=$

$N(t)=$

$($b$)$ Use this formula to find the curvature.

$(t)=$

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