Divide a circle into several equal parts and join them into an approximate rectangle. The perimeter of the approximate rectangle is increased by 8 cm. What is the area of the original circle?
把一个圆分成若干等份后拼接成一个近似的长方形，近似的长方形的周长增加了8厘米，求原来圆的面积是多少？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>