After cutting a circular piece of paper, assemble it into an approximate rectangle whose width is equal to the radius and area. The perimeter of this rectangle is 16.56 cm. What is the area of this circular piece of paper? (π takes 3.14)
把一个圆形纸片剪开后，拼成一个宽等于半径，面积相等的近似长方形．这个长方形的周长是16.56厘米，原来这个圆形纸片的面积是多少．(π取3.14)
<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

<gadget id="calculator">2 + 6.28</gadget>
<output>8.28</output>

<gadget id="calculator">16.56 / 8.28</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

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

<result>12.56</result>