Draw the largest circle in a rectangle with a length of 8 cm and a width of 4 cm. What is the circumference of the circle?
在长8厘米，宽4厘米的长方形中画一个最大的圆，圆的周长是多少．
<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>