A cylinder with a height of 55 cm is cut in half along the center of the upper and lower bases. The surface area is increased by 20 square centimeters. What is the lateral area of the cylinder?
一个圆柱体，高55厘米，沿上下底圆心切成两半，表面积增加了20平方厘米，圆柱体侧面积是多少．
<gadget id="calculator">20 / 2 / 55</gadget>
<output>2/11 = around 0.181818</output>

<gadget id="calculator">3.14 * (2/11) * 55</gadget>
<output>31.4</output>

<result>31.4</result>