A circular flower bed is 40 meters in diameter, and a path with a width of 1 meter is built around it. What is the area of the path in square meters?
一个圆形花坛，直径40米，在它的四周修一条宽1米的小路，小路的面积是多少平方米？
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 ** 2</gadget>
<output>441</output>

<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">441 - 400</gadget>
<output>41</output>

<gadget id="calculator">3.14 * 41</gadget>
<output>128.74</output>

<result>128.74</result>