If the circumference of a semicircle is 15.42 cm, what is the area of the semicircle?
一个半圆的周长是15.42cm，则这个半圆的面积是多少．
<gadget id="calculator">15.42 / 5.14</gadget>
<output>3</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">3.14 * 3 * (3/2)</gadget>
<output>14.13</output>

<result>14.13</result>