[tex]\bf \textit{arc's length}\\\\ s=\cfrac{\theta \pi r}{180}~~ \begin{cases} r=radius\\ \theta =angle~in\\ \qquad degrees\\[-0.5em] \hrulefill\\ r=6\\ \theta =45 \end{cases}\implies s=\cfrac{(45)\pi (6)}{180}\implies s=\cfrac{3\pi }{2}\implies s\approx 4.7[/tex]