If a cylinder with a base diameter of 6 cm and a height of 15 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6cm，高为15cm的圆柱体沿直径切割成两个半圆柱，表面积增加多少．
<gadget id="calculator">6 * 15 * 2</gadget>
<output>180</output>

<result>180</result>