Make a ventilation pipe with a bottom radius of 5 cm and a height of 100 cm, what is its lateral area in square centimeters?
做一节底面半径5厘米，高100厘米的通风管，它的侧面积是多少平方厘米．
<gadget id="calculator">3.14 * 5 * 2 * 100</gadget>
<output>3_140</output>

<result>3_140</result>