rectangular iron sheet with a length of 28.26 cm and a width of 15.7 cm should be matched with a circular iron sheet with a diameter of how many centimeters to make a container with the largest volume.
用一块长28.26厘米、宽15.7厘米的长方形铁皮，应配上直径是多少厘米的圆形铁皮，可以做成一个容积最大的容器．
<gadget id="calculator">28.26 / 3.14 / 2</gadget>
<output>4.5</output>

<gadget id="calculator">4.5 * 2</gadget>
<output>9</output>

<result>9</result>