cylinder, if its height is shortened by 3 centimeters, the surface area will be reduced by 94.2 square centimeters, what is the radius of the base of the cylinder?
一个圆柱体，如果把它的高截短了3厘米，表面积就减少94.2平方厘米，圆柱体的底面半径是多少．
<gadget id="calculator">94.2 / 3 / 3.14 / 2</gadget>
<output>5</output>

<result>5</result>