If the difference between the circumferences of the two circles is 18.84 centimeters, what is the difference in centimeters between the radii of the two circles?
两圆周长之差为18.84厘米，那么这两个圆的半径之差是多少厘米．
<gadget id="calculator">2 * 3.14</gadget>
<output>6.28</output>

<gadget id="calculator">18.84 / 6.28</gadget>
<output>3</output>

<result>3</result>