A sheep is tied to a stake in a lawn with a rope length of 5 meters. What is the maximum area of grass that this sheep can eat?
在一块草坪地的木桩上拴着一只羊，绳长5米．这只羊最多能吃着草地的面积是多少平方米？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>