A cylindrical piece of wood is 16 decimeters long and has a radius of 3 decimeters. How many decimeters does the surface area increase when it is sawn in two?
一个圆柱形木料长16分米，半径是3分米，把它锯成两段后，表面积增加了多少分米．
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9 * 2</gadget>
<output>56.52</output>

<result>56.52</result>