Cut a square paper with a side length of 6 cm into a circle with the largest area. What is the area of this circle?
把边长6厘米的正方形纸剪成一个面积最大的圆形，这个圆形的面积是多少．
<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>