Cut a cylinder along a diameter perpendicular to the bottom surface. The cut surface is exactly a square with a side length of 4 cm. What is the surface area of the cylinder?
沿着一个圆柱的一条直径垂直于底面把它切开，切面正好是一个边长4cm的正方形，这个圆柱的表面积是多少．
<gadget id="calculator">3.14 * 4 * 4</gadget>
<output>50.24</output>

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

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

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<gadget id="calculator">50.24 + 25.12</gadget>
<output>75.36</output>

<result>75.36</result>