The circumference of a semicircle is 51.4 cm, what is its area in square centimeters?
半圆的周长为51.4厘米，它的面积是多少平方厘米．
<gadget id="calculator">3.14 + 2</gadget>
<output>5.14</output>

<gadget id="calculator">51.4 / 5.14</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<gadget id="calculator">3.14 * 50</gadget>
<output>157</output>

<result>157</result>