If a cylinder with a base radius of 2cm is expanded sideways, a square can be obtained. What is the height of the cylinder in cm?
把一个底面半径是2cm的圆柱侧面展开，可得到一个正方形，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>