A cylinder is enclosed by a square with a perimeter of 12.56 cm. Two bases are to be made for the cylinder. What is the radius of the base?
用一个周长是12.56厘米的正方形围成一个圆柱，要给圆柱做两个底面，底面半径是多少？
<gadget id="calculator">12.56 / 4</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 / 3.14 / 2</gadget>
<output>0.5</output>

<result>0.5</result>