Given that the circumference of a semicircle is 51.4 cm, find the area of the circle.
已知一个半圆的周长是51.4厘米，求这个圆的面积．
<gadget id="calculator">51.4 / 5.14</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>