Find an arc length parametrization $\bf r\it_1(s)$ of ${\bf r}({\it t})=\left<e^{t}\sin\!\left(t\right),e^{t}\cos\!\left(t\right),3e^{t}\right>$.
Assume $t(s)=0$ when $s=0$, and $t'(0)>0$.

${\bf r\it_1(s)}=\left< \right.$ ,, $\left. \right>$