The top of the lampshade is circular in shape
[tex]\begin{gathered} \text{The circumference of a circle = 2}\pi r \\ \text{where }\pi=3.14,\text{ r= radius of the circle} \\ \text{The radius , r=9 in} \\ \text{Circumference = 2 x 3.14 x }9 \\ \text{Circumference = }56.52\text{ in} \end{gathered}[/tex]The circumference of the top of the shade is 56.52 inches
