Cut a circle into a rectangle with the same area and increase the circumference by 8 cm. What is the area of the circle in square centimeters?
把一个圆剪拼成一个面积相等的长方形，周长增加8厘米，这个圆的面积是多少平方厘米？
<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>