A square is obtained after unfolding the sides of a cylinder. It is known that the radius of the base of this cylinder is 5 cm. What is its height?
把一个圆柱侧面展开后得到一个正方形，已知这个圆柱体底面半径是5厘米，它的高是多少？
<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<result>31.4</result>