A sheep is tied to a tree in the middle of the grass. It is known that the length of the rope tied to the sheep is 5 meters. How many square meters of grass can the sheep eat at most?
一只羊被拴在草地中央的一棵树上，已知栓羊的绳子长5米，这只羊最多能吃到多少平方米范围内的草？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

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

<result>78.5</result>