On a round clock face, the hour hand is 3 cm long. After 12 hours, what is the area swept by the hour hand?
在一只圆形钟面上，时针长3厘米．经过12小时，时针扫过的面积是多少平方厘米？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>