Answer: We have to find the arc length of the semi-circle shown, the arc length would be half of the circumference, and is calculated as follows:
[tex]\begin{gathered} L_{arc}=\frac{C}{2} \\ C=2\pi r=2\cdot\pi\cdot\frac{12}{2} \\ C=12\pi \\ \therefore\Rightarrow \\ L_{arc}=\frac{12\pi}{2}=6\pi \\ L_{arc}=6\pi \end{gathered}[/tex]
Therefore the arch length is 6pi.
