A cylinder has a base diameter of 4 cm and a height of 15 cm, what is its lateral area in cm**2.
一个圆柱的底面直径是4cm，高是15cm，它的侧面积是多少cm**2．
<gadget id="calculator">3.14 * 4 * 15</gadget>
<output>188.4</output>

<result>188.4</result>