The diameter of a circular fountain is 8 meters, and a cement road with a width of 2 meters is built around the pool. Find the area of the road.
在一个圆形喷水池的直径是8米，绕着这个水池修一条宽2米的水泥路．求路面的面积．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 2</gadget>
<output>6</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

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

<gadget id="calculator">36 - 16</gadget>
<output>20</output>

<gadget id="calculator">3.14 * 20</gadget>
<output>62.8</output>

<result>62.8</result>