Answer:
[tex]\large\boxed{\dfrac{C}{d}=\pi}[/tex]
Step-by-step explanation:
We have the radius r = 9.
The formula of a circumference of a circle:
[tex]C=2\pi r[/tex]
The diameter d = 2r.
The ratio of the circumference of the circle to the circle's diameter:
[tex]\dfrac{C}{d}=\dfrac{2\pi r}{2r}=\pi[/tex]
