A sheep is tied to a stump in the middle of a meadow, and the length of the rope from the stump to the neck of the sheep is 3 meters. How many square meters of grass can this sheep eat?
一只羊栓在一块草地中央的树桩上，树桩到羊颈的绳长是3米．这只羊可以吃到多少平方米地面的草．
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<result>28.26</result>