Grandma Wang used a 31.4-meter-long fence to form a semicircular chicken farm. What is the area of the chicken farm?
王奶奶用31.4米长的篱笆靠墙围成一个半圆形的养鸡场，这个养鸡场的占地面积是多少？
<gadget id="calculator">31.4 * 2</gadget>
<output>62.8</output>

<gadget id="calculator">62.8 / 3.14 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<result>314</result>