There is a stake on the grass, and a sheep is tied to the stake with a 2m long rope, the joints are not counted. How many square meters of grass can this sheep eat at most?
草地上有一木桩，把一只羊用一根长2m的绳子系在木桩上，接头处不计算．这只羊最多能吃到多少平方米的草？
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>