The outer diameter of the cement pipe in the sewer is 1.2 meters, and the inner diameter is 1 meter. What is its annular cross-sectional area?
下水道的水泥管道外圆直径是1.2米，内圆直径是1米，它的环形截面面积是多少？
<gadget id="calculator">1.2 / 2</gadget>
<output>0.6</output>

<gadget id="calculator">0.6 ** 2</gadget>
<output>0.36</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) ** 2</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">0.36 - (1/4)</gadget>
<output>0.11</output>

<gadget id="calculator">3.14 * 0.11</gadget>
<output>0.3454</output>

<result>0.3454</result>