What is the area in square centimeters of a semicircular part whose circumference is 25.7 centimeters?
一个半圆形零件，周长是25.7厘米，它的面积是多少平方厘米．
<gadget id="calculator">3.14 * 5 * 5</gadget>
<output>78.5</output>

<result>78.5</result>