Draw the largest semicircle in a rectangle with a length of 12 cm and a width of 8 cm. What is the circumference of the semicircle in cm?
在长12厘米，宽8厘米的长方形内，画出一个最大的半圆，半圆的周长是多少厘米．
<gadget id="calculator">3.14 * 12</gadget>
<output>37.68</output>

<gadget id="calculator">37.68 / 2</gadget>
<output>18.84</output>

<gadget id="calculator">18.84 + 12</gadget>
<output>30.84</output>

<result>30.84</result>