In a rectangle with a length of 5 meters and a width of 4 meters, construct the largest circle, compare the circumference of this circle with the circumference of the rectangle, which one is longer? How long?
在长5米、宽4米的长方形中，作一个最大的圆，这个圆的周长与长方形的周长比较，哪一个长？长多少？
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">18 - 12.56</gadget>
<output>5.44</output>

<result>5.44</result>