Given, the circumference of the circle, C=12π.
The circumference of a circle can be expressed as,
[tex]C=2\pi\text{ r}[/tex]Here, r is the radius of the circle.
Put C=12π in the above equation to find radius r.
[tex]\begin{gathered} 12\pi=2\pi r \\ r=\frac{12\pi}{2\pi} \\ =6 \end{gathered}[/tex]The diameter of the circle is,
[tex]\begin{gathered} D=2r \\ =2\times6=12 \end{gathered}[/tex]Therefore, the radius of the circle is 6 and the diameter of the circle is 12.
