If a cylinder with a base diameter of 3 cm and a height of 5 cm is cut into two half cylinders along the diameter, how much is the surface area increased?
把一个底面直径为3厘米、高是5厘米的圆柱体沿直径切割成两个半圆柱，表面积增加了多少．
<gadget id="calculator">3 * 5 * 2</gadget>
<output>30</output>

<result>30</result>