A cylinder with a height of 5 cm is increased by 2 cm and its surface area increases by 12.56 cm2. What is the original lateral area of the cylinder in cm2?
一个高5厘米的圆柱增高2厘米后表面积增加12.56平方厘米，这个圆柱原来的侧面积是多少平方厘米．
<gadget id="calculator">12.56 / 2</gadget>
<output>6.28</output>

<gadget id="calculator">6.28 * 5</gadget>
<output>31.4</output>

<result>31.4</result>