The expansion of the lateral area of a cylinder is exactly a square, the radius of the base of the cylinder is 2 decimeters, and the height of the cylinder is how many decimeters.
一个圆柱的侧面积展开恰好是一个正方形，圆柱的底面半径是2分米，圆柱的高是多少分米．
<gadget id="calculator">3.14 * 2 * 2</gadget>
<output>12.56</output>

<result>12.56</result>