If the perimeter of a semicircular piece of paper is 10.28 decimeters, what is its area in square decimeters?
一个半圆形纸片的周长是10.28分米，它的面积是多少平方分米．
<gadget id="calculator">3.14 + 2</gadget>
<output>5.14</output>

<gadget id="calculator">10.28 / 5.14</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

<result>6.28</result>