There is a cylinder with a base diameter of 6 cm, if its height increases by 2 cm, how much does the surface area increase by π square centimeters?
有一个圆柱体，底面直径是6厘米，如果它的高增加2厘米，则表面积增加多少π平方厘米．
<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<result>12</result>