There is a circular flower bed with a diameter of 20 meters in the park. A cement road with a width of 2 meters is laid around it. Find the area of the cement road.
公园里有一个直径为20米的圆形花坛，在它的周围铺设2米宽的水泥路，求这条水泥路的面积．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 2</gadget>
<output>12</output>

<gadget id="calculator">12 ** 2</gadget>
<output>144</output>

<gadget id="calculator">3.14 * 144</gadget>
<output>452.16</output>

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

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">452.16 - 314</gadget>
<output>138.16</output>

<result>138.16</result>