There is a sheep tied to a stake on the grassland. The length of the rope tied to the sheep is 4 meters. What is the largest area in square meters that the sheep can eat grass?
在草原上有一头羊栓在一个木桩上，栓羊的绳子长4米，羊能吃到草的面积最大是多少平方米？
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>