A square is obtained by unfolding the sides of a cylinder with a base radius of 2 cm. What is the height of the cylinder in cm?
把一个底面半径为2cm的圆柱的侧面展开，得到一个正方形，这个圆柱的高是多少cm．
<gadget id="calculator">2 * 3.14 * 2</gadget>
<output>12.56</output>

<result>12.56</result>