If you cut a circle into a rectangle with the same area as it, and the circumference is increased by 6 cm, what is the area of the circle in square centimeters?
把一个圆剪拼成一个和它面积相等的长方形，周长增加了6厘米，原来这个圆的面积是多少平方厘米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>