Expand the side of a cylinder to get a rectangle with a length of 12.56 cm and a width of 3 cm. What is the side area of the cylinder in square centimeters?
把一个圆柱的侧面展开，得到一个长12.56厘米、宽3厘米的长方形，这个圆柱的侧面积是多少平方厘米．
<gadget id="calculator">12.56 * 3</gadget>
<output>37.68</output>

<result>37.68</result>