How many square centimeters of iron sheet should be used to make a cylindrical ventilation pipe with a bottom diameter of 30cm and a length of 60cm?
制作一个底面直径是30cm、长60cm的圆柱形通风管，至少要用多少平方厘米铁皮？
<gadget id="calculator">3.14 * 30 * 60</gadget>
<output>5_652</output>

<result>5_652</result>