Divide a circle into several equal parts and assemble them into approximate rectangles. The perimeter of the assembled rectangle is 16.56cm, what is the area of the circle in cm**2. ．
把一个圆分成若干等分，拼成近似的长方形．拼成的长方形的周长是16.56cm，圆的面积是多少cm**2．．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>