The lateral expansion of a cylinder is a square, and its radius is 2dm. What is the height of the cylinder in dm?
一个圆柱的侧面展开是一个正方形，它的半径是2dm，这个圆柱高多少dm．
<gadget id="calculator">2 * 3.14 * 2</gadget>
<output>12.56</output>

<result>12.56</result>