[tex]\begin{gathered} (1)radius\text{ = }\frac{Diameter}{2} \\ \text{Diameter = 2 }\times\text{ radius} \\ \text{Diameter = 2 }\times\text{ 7} \\ \text{Diameter = 14mm} \\ \\ (2)\text{ Circumference = 2}\times\pi\times\text{ r} \\ \text{Circumference = 2}\times\pi\times\text{ 7} \\ \text{Circumference = }14\pi \\ (3)\text{Circumference = 2}\times\frac{22}{7}\times7 \\ \text{Circumference = }44\operatorname{mm} \end{gathered}[/tex]
