A cylinder is formed by a piece of paper with a length of 5 cm and a width of 3 cm. What is the lateral area of the cylinder?
用一张长5厘米，宽3厘米的纸围成一个圆柱，这个圆柱的侧面积是多少．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>