[tex]Solution; \\ \\ \pi = \frac{22}{7} \\ diameter=2.1\ cm. \\ \\ Formula; \\ Circumference= \pi \times diameter \\ \\ Circumference= \frac{22}{7}\times2.1 \\ \\ Circumference= \frac{46.2}{7} \\ \\ \boxed{\boxed{Circumference=6.6}} \\ \\ Hope\ it\ Helps :) \\ Domini [/tex]
