If a cylinder with a base radius of 3 cm is expanded sideways to obtain a square, what is the height of the cylinder in centimeters?
把一个底面半径是3厘米的圆柱体侧面展开，得到一个正方形，这个圆柱体的高是多少厘米．
<gadget id="calculator">2 * 3.14 * 3</gadget>
<output>18.84</output>

<result>18.84</result>