Round Picnic Table

Jim bought a round picnic table. The diameter of this table is 12.

What is the area and circumference of Jim’s picnic table?

$\begin{array}{rcll} \text{diameter }~ d &=& 12 \\\\ \text{radius } ~r &=& \frac{d}{2} \\ r &=& \frac{12}{2} \\ r &=& 6\\\\ \text{area } ~ a &=& \pi\cdot r^2 \\ a &=& \pi\cdot 6^2 \\ a &=& \pi\cdot 36 \\\\ \text{circumference } ~ c &=& 2\cdot \pi\cdot r \\ c &=& 2\cdot \pi\cdot 6 \\ c &=& \pi\cdot 12 \\\\ a &=& 36\cdot \pi \\ a &=& 36\cdot 3.14159265359\\ \mathbf{a} &\mathbf{=}& \mathbf{113.097335529} \\\\ c &=& 12\cdot \pi \\ c &=& 12\cdot 3.14159265359\\ \mathbf{c} &\mathbf{=}& \mathbf{37.6991118431} \end{array}$