The side area of a cylinder is 188.4dm**2, the diameter of the bottom is 4dm, what is its height in dm.
一个圆柱的侧面积是188.4dm**2，底面直径是4dm，它的高是多少dm．
<gadget id="calculator">188.4 / 3.14 / 4</gadget>
<output>15</output>

<result>15</result>