Xiao Ming tied a sheep to a stake when herding sheep. The length of the rope from the stake to the neck of the sheep was 5 meters. What is the grazing range of this sheep in square meters?
小明放羊时把一只羊栓在木桩上，木桩到羊颈项的绳长5米，求这只羊的吃草范围是多少平方米？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

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

<result>78.5</result>