A cylinder expanded laterally is a square. If the diameter of the base of the cylinder is 5 cm, what is the height of the cylinder?
一个圆柱体侧面展开是一个正方形．若这个圆柱底面直径是5厘米，这个圆柱的高是多少．
<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>