how to compute the arclength function $\displaystyle s(t) $with the curve $\displaystyle r=(e^t cos(-3t),e^t sin(-3t),e^t)$....i got stuck when i was doing the derivative parts.

And also how to find the length of curve if i given two points with $\displaystyle r(t)$, for example, if i have $\displaystyle r(t)=(10t,5t^2,5 Int)$ and i have to find the length of curve with points, $\displaystyle (10,5,0)$ and $\displaystyle (50,125, 5 In(5))

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Help =( Plz help..