The lateral expansion of a cylinder is a square with a radius of 3 decimeters. What is the height of the cylinder?
一个圆柱的侧面展开是正方形，半径是3分米，这圆柱体的高是多少．
<gadget id="calculator">2 * 3.14 * 3</gadget>
<output>18.84</output>

<result>18.84</result>