The volume ratio of a cone to a cylinder is 1:2, the ratio of the base area is 3:4, and the height of the cylinder is 9 cm. What is the height of the cone in centimeters.
一个圆锥与一个圆柱的体积比是1：2，底面积之比是3：4，圆柱的高是9厘米．圆锥的高是多少厘米．
<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>