The circumference of a semicircle is 30.84 meters, what is the area of the semicircle in square meters?
半圆的周长为30.84米，半圆的面积为多少平方米．
<gadget id="calculator">30.84 / 5.14</gadget>
<output>6</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3.14 * 6 * 3</gadget>
<output>56.52</output>

<result>56.52</result>