A cylindrical cup without a lid has a bottom diameter of 8 cm and a height of 10 cm. What is its surface area in cm**2.
一个圆柱形无盖茶杯，底面直径为8cm、高为10cm，它的表面积是多少cm**2．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<gadget id="calculator">3.14 * 8 * 10</gadget>
<output>251.2</output>

<gadget id="calculator">50.24 + 251.2</gadget>
<output>301.44</output>

<result>301.44</result>