If a cylinder with a base diameter of 10 cm and a height of 20 cm is cut in half along its diameter perpendicular to the base, how many square centimeters will the surface area increase?
一个底面直径是10厘米、高是20厘米的圆柱体，如果把它沿直直径垂直于底面切成两半，表面积增加了多少平方厘米．
<gadget id="calculator">10 * 20 * 2</gadget>
<output>400</output>

<result>400</result>