Lili does handwork, first cut out a ring with a piece of hard paper, then draw a red line along the inner line of the ring, and draw a yellow line along the outer line, the known ring width is 5cm, how many cm longer is the yellow line than the red line ．
丽丽做手工，先用硬纸片剪战出一个圆环，接着沿圆环的内沿线画一条红线，沿外沿线画一条黄线，已知环宽是5cm，黄线比红线长多少cm．
<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<result>31.4</result>