Cut the largest circle out of a rectangle with a length of 10 cm and a width of 7 cm, what is the circumference of the circle?
在长10厘米，宽7厘米的长方形中剪一个最大的圆，求圆的周长？
<gadget id="calculator">3.14 * 7</gadget>
<output>21.98</output>

<result>21.98</result>