The lateral area of a cylinder is 31.4 square decimeters, the height is 2 decimeters, what is the radius of its bottom surface in decimeters?
一个圆柱体的侧面积是31.4平方分米，高是2分米，它的底面半径是多少分米．
<gadget id="calculator">31.4 / 2 / 3.14 / 2</gadget>
<output>2.5</output>

<result>2.5</result>