Unfold the sides of a cylinder to obtain a square with side length 15 cm. What is the lateral area of this cylinder? ?
将一个圆柱的侧面展开，得到一个边长是15厘米的正方形．这个圆柱的侧面积是多少？？
<gadget id="calculator">15 * 15</gadget>
<output>225</output>

<result>225</result>