What is the area of a semicircle with a circumference of 25.7m in m**2.
一个周长为25.7m的半圆，它的面积是多少m**2．
<gadget id="calculator">3.14 + 2</gadget>
<output>5.14</output>

<gadget id="calculator">25.7 / 5.14</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">25 / 2</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">3.14 * (25/2)</gadget>
<output>39.25</output>

<result>39.25</result>