The perimeter of a semicircle is 25.7 cm, what is the area of the semicircle in square centimeters?
一个半圆形的周长是25.7厘米，这个半圆的面积是多少平方厘米．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">25 / 2</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">3.14 * (25/2)</gadget>
<output>39.25</output>

<result>39.25</result>