The side view of a cylinder is a square. The height of the cylinder is 6.28cm. What is the diameter of the bottom surface of the cylinder in cm?
一个圆柱的侧面展开图是一个正方形，量得圆柱的高是6.28cm，圆柱的底面直径是多少cm．
<gadget id="calculator">6.28 / 3.14</gadget>
<output>2</output>

<result>2</result>