After Xiaoqing wraps a 20m long rope around a circular tree trunk 3 times, there is still 1.16m left. What is the cross-sectional area of this tree trunk in square meters?
小青用一根长20m的绳子绕一棵圆形树干3圈后，还余1.16m，这棵树干的横截面的面积是多少平方米？
<gadget id="calculator">20 - 1.16</gadget>
<output>18.84</output>

<gadget id="calculator">18.84 / 3 / 3.14 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<result>3.14</result>