The circumference of a semicircle is 10.28cm, what is the area of a circle with the same size in cm**2.
一个半圆的周长是10.28cm，和它大小相等的圆的面积是多少cm**2．
<gadget id="calculator">10.28 / 2.57 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>