Cut out the largest semicircle from a rectangular piece of paper with a length of 8 cm and a width of 4 cm. What is the circumference of the cut semicircle in cm?
在一个长8厘米、宽4厘米的长方形纸片上剪下一个最大的半圆，剪下的半圆的周长是多少厘米．
<gadget id="calculator">3.14 * 8</gadget>
<output>25.12</output>

<gadget id="calculator">25.12 / 2</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 + 8</gadget>
<output>20.56</output>

<result>20.56</result>