We have that the base of the cylinder is a circle, and the area of a circle can be calculated with the following equation:
[tex]B=\pi\cdot r^2[/tex]In this case, we have the following:
[tex]\begin{gathered} \pi=3.14 \\ r=\frac{d}{2}=\frac{6}{2}=3 \\ \Rightarrow B=(3.14)(3)^2=(3.14)(3)(3) \end{gathered}[/tex]therefore, the area of the base is B=(3.14)(3)(3) = 28.26 cm^2