Given that the circumference of a semicircle is 15.42 decimeters, what is the area of this semicircle in square decimeters?
已知一个半圆的周长是15.42分米，求这个半圆的面积是多少平方分米？
<gadget id="calculator">15.42 / 5.14</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">3.14 * (9/2)</gadget>
<output>14.13</output>

<result>14.13</result>