There is a stake in the grass, and a sheep is tied to the stake with a 3-meter-long rope. How many square meters of grass can the sheep eat at most?
草地上有一个木桩，用一根3米长的绳子把一只羊拴在木桩上，这只羊最多可以吃到多少平方米的草？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<result>28.26</result>