Given a cricle with radius "r", the diameter "d" is related by:
[tex]\begin{gathered} d=2r \\ r=\frac{d}{2} \end{gathered}[/tex]For this circle, the circumference can be calculated by:
[tex]c=2\pi r[/tex]We have d = 9 in and π = 3.14. So:
[tex]r=\frac{9}{2}=4.5[/tex][tex]c=2\pi r=2\cdot3.14\cdot4.5=28.26[/tex]So, the circumference is 28.26 in.