The radius of the base of a cylindrical paper tube is 5cm, and its side wrapping paper is unfolded to form a square. What is the lateral area of the cylinder?
一个圆柱形纸筒的底面半径为5cm，它的侧面包装纸展开后是一个正方形，这个圆柱的侧面积是多少？
<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<gadget id="calculator">2 * 3.14 * 5 * 31.4</gadget>
<output>985.96</output>

<result>985.96</result>