If the side of a cylinder is expanded to obtain a square with a side length of 12 cm, what is the side area of the cylinder in square centimeters?
把一个圆柱的侧面展开得到一个边长为12厘米的正方形，这个圆柱的侧面积是多少平方厘米？
<gadget id="calculator">12 * 12</gadget>
<output>144</output>

<result>144</result>