There is a circular flower bed in the park with a diameter of 18 meters. A circular cross road with a width of 1 meter is built around it. What is the area of this gravel road in square meters?
公园里有一个圆形花坛，直径是18米，在它的周围建一条1米宽的环形十字路，这条石子路的面积是多少平方米？
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">9 ** 2</gadget>
<output>81</output>

<gadget id="calculator">100 - 81</gadget>
<output>19</output>

<gadget id="calculator">3.14 * 19</gadget>
<output>59.66</output>

<result>59.66</result>