There is a cowshed surrounded by a piece of green grass. The cowshed is 5 meters long and 4 meters wide. A cow is tied to a corner of the cowshed with a rope. The rope is 9 meters long. What is the largest area of green grass that the cow can eat? How many square meters? (not counting the area inside the cowshed)
有一个牛棚，周围是一片青草，牛棚长5米，宽4米，牛棚的一角用一根绳子拴着一头牛，绳子长9米，问这头牛能吃到的青草的面积最多有多少平方米？(不算牛棚内的面积)
<gadget id="calculator">9 ** 2</gadget>
<output>81</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">3.14 * 81 * (3/4)</gadget>
<output>190.755</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3.14 * 25 * (1/4)</gadget>
<output>19.625</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16 * (1/4)</gadget>
<output>12.56</output>

<gadget id="calculator">190.755 + 19.625 + 12.56</gadget>
<output>222.94</output>

<result>222.94</result>