Uncle Wang tied the sheep to a tree with a 2-meter-long rope. What is the maximum range in which the sheep can move?
王大伯用2米长的绳子把羊拴在一棵树上，这只羊能够活动的范围最大是多少平方米？
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

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

<result>12.56</result>