A sheep is tied with a 3-meter-long rope to a stake in the middle of a grassland. How many square meters of grass can this sheep eat at most?
在一片草地中央的木桩上用3米长的绳子拴一只羊，这只羊最多能吃多少平方米的草？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<result>28.26</result>