After unfolding the sides of a cylinder, a square is obtained. If the radius of the bottom of the cylinder is 5cm, what is the height of the cylinder in cm?
把一个圆柱体的侧面展开后，得到一个正方形，若这个圆柱体底面半径是5cm，那么圆柱体的高是多少cm．
<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<result>31.4</result>