When deriving the formula for the area of a circle, divide the circle into several parts and put together an approximate rectangle. The width of the rectangle is known to be 2 cm. What is the area of the circle in cm**2.
在推导圆的面积公式时，将圆等分成若干份，拼成一个近似的长方形，已知长方形的宽是2cm，这个圆的面积是多少cm**2．
<gadget id="calculator">3.14 * 2 * 2</gadget>
<output>12.56</output>

<result>12.56</result>