Draw the largest semicircle in a rectangle with a length of 6 decimeters and a width of 4 decimeters. What is the circumference of the semicircle in decimeters?
在长6分米，宽4分米的长方形中画一个最大的半圆，半圆的周长多少分米？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<gadget id="calculator">9.42 + 6</gadget>
<output>15.42</output>

<result>15.42</result>