A factory produces a circular gasket for machine parts. The outer radius of this annular gasket is 3 cm and the inner radius is 2 cm. What is the area of this spacer?
一家工厂生产一种环形的机器零件垫片，这种环形垫片的外半径是3cm，内半径是2cm．这种垫片的面积是多少？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<gadget id="calculator">9 - 4</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>