Cut a largest circle on a cardboard with a length of 8 meters and a width of 6 meters. What is the area of this circle?
在一个长8米，宽6米的硬纸板上剪一个最大的圆，这个圆的面积是多少．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>