[tex]\textit{arc's length}\\\\ s=\cfrac{\theta \pi r}{180} ~~ \begin{cases} r=radius\\ \theta =\stackrel{degrees}{angle}\\[-0.5em] \hrulefill\\ r=2\\ \theta =36 \end{cases}\implies s=\cfrac{(36)\pi (2)}{180}\implies s=\cfrac{2\pi }{5}\implies s\approx 1.26~in[/tex]
