From one end of a cylinder with a base radius of 4 cm, cut across the next section. If the side view of the cut cylinder is to be a square, what is the length of the cut cylinder in centimeters?
从一个底面半径为4厘米的圆柱的一端，横截下一段，要使截下的圆柱的侧面展开图为正方形，则截下的圆柱长为多少厘米．
<gadget id="calculator">2 * 3.14 * 4</gadget>
<output>25.12</output>

<result>25.12</result>