Divide a circle into several parts on average, and assemble it into an approximate rectangle. The width of the assembled approximate rectangle is 2 cm. What is the area of the original circle?
将一个圆平均分成若干份，拼成一个近似长方形，拼成的近似长方形的宽是2厘米，原来这个圆的面积是多少．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>