What is the arc length of ab?
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[tex]\textit{arc's length}\\\\ s=\cfrac{\theta \pi r}{180} ~~ \begin{cases} r=radius\\ \theta =\stackrel{degrees}{angle}\\[-0.5em] \hrulefill\\ r=13\\ \theta =115 \end{cases}\implies \begin{array}{llll} s=\cfrac{(115)\pi (13)}{180}\implies s=\cfrac{299\pi }{36} \\\\\\ s\approx 26.09~in \end{array}[/tex]