When Grandpa Wang herded sheep, he tied a sheep to a stake. The rope from the stake to the neck of the sheep was 3 meters long. What is the maximum area that the sheep can eat grass in square meters?
王爷爷放羊时，把一只羊栓在木桩上，木桩到羊颈的绳子长3米，这只羊能吃到草的面积最大是多少平方米？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<result>28.26</result>