Cut a cylinder with a base diameter of 5 cm and a height of 8 cm along the base diameter and divide it into two parts with the same shape and size. How much does their surface area increase compared to the original one?
把一个底面直径为5厘米，高是8厘米的圆柱体沿底面直径切开，分成形状大小完全相同的两部分，它们的表面积比原来增加多少．
<gadget id="calculator">5 * 8 * 2</gadget>
<output>80</output>

<result>80</result>