Divide a circular piece of paper into several equal parts along the radius, and put together an approximate rectangle. The perimeter of the rectangle is known to be 16.56 cm. What is the area of the circle in square centimeters?
把一张圆形纸片沿半径平均分成若干份，拼成一个近似长方形，已知长方形的周长是16.56厘米，这个圆的面积是多少平方厘米？
<gadget id="calculator">16.56 / 8.28</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 2 * 2</gadget>
<output>12.56</output>

<result>12.56</result>