Answer:
\(7 \pi\ mm\)
Step-by-step explanation:
we know that
The circumference of a circle is equal to
\(C=2\pi r\)
In this problem we have
\(r=21\ mm\)
substitute
\(C=2\pi (21)=42\pi\ mm\)
\(360\°\) subtends the complete circle of length equal to \(42\pi\ mm\)
so by proportion
Find the length of arc which a central angle of \(60\°\)
\(\frac{42\pi}{360}\frac{\ mm}{degrees}=\frac{x}{60}\frac{\ mm}{degrees} \\ \\x=42\pi *60/360\\ \\ x= 7 \pi\ mm\)
