A rectangular fence with a length of 4 meters and a width of 2 meters is surrounded in an open grassland. Now tie a cow to a corner of the fence. The rope is 2 meters long. What is the maximum area in square meters that the cow can eat grass?
在一片空旷的草地中圈了一个长4米、宽2米的长方形栅栏，现将一头牛栓在栅栏的一角，绳子长2米，牛能吃到草的最大面积多少平方米．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3.14 * 4 * (1/2)</gadget>
<output>6.28</output>

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

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

<gadget id="calculator">6.28 + 3.14</gadget>
<output>9.42</output>

<result>9.42</result>