Consider the following vector function.

$r(t)=($:$8sin(t),t,8cos(t)$:$)$

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

$T(t)=$

$N(t)=$

$($b$)$ Use the formula $(t)=\frac{|T^{\text{'}}(t)|}{|r^{\text{'}}(t)|}$ to find the curvature.

$(t)=$