ANSWER:
The circumference is equal to 37.68 units
STEP-BY-STEP EXPLANATION:
The circumference of a circle has the following formula
[tex]c=2\cdot\pi\cdot r[/tex]We know that the radius is equal to half the diameter, therefore, we replace and we have:
[tex]\begin{gathered} r=\frac{d}{2}=\frac{12}{2}=6 \\ \text{replacing:} \\ c=2\cdot3.14\cdot6 \\ c=37.68 \end{gathered}[/tex]