A cylinder whose base circumference is equal to its height, if the height increases by 1 cm, its surface area will increase by 6.28 cm2, what is the circumference of its base in cm?
一个底面周长和高相等的圆柱体，如果高增加1厘米，它的表面积就增加6.28平方厘米，它的底面周长是多少厘米．
<gadget id="calculator">6.28 / 1</gadget>
<output>6.28</output>

<result>6.28</result>