A circular fish pond has a circumference of 47.1 meters, what is the surface area of the pond?
一个圆形的鱼池，周长47.1米，池面的面积是多少？
<gadget id="calculator">47.1 / 3.14 / 2</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 ** 2</gadget>
<output>56.25</output>

<gadget id="calculator">3.14 * 56.25</gadget>
<output>176.625</output>

<result>176.625</result>