If the lateral expansion of a cylinder is a square with a side length of 31.4 cm, what is the radius of the base of the cylinder in cm?
一个圆柱的侧面展开是一个边长31.4厘米的正方形，这个圆柱的底面半径是多少厘米．
<gadget id="calculator">31.4 / 3.14 / 2</gadget>
<output>5</output>

<result>5</result>