When deriving the formula for the area of a circle, divide the circle into several equal parts and put together an approximate rectangle. It is known that the sum of the length and width of the rectangle is 8.28 cm. What is the area of the circle in square centimeters?
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，已知长方形的长与宽的和是8.28厘米，圆的面积是多少平方厘米．
<gadget id="calculator">3.14 + 1</gadget>
<output>4.14</output>

<gadget id="calculator">8.28 / 4.14</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

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

<result>12.56</result>