Draw the largest circle in a square with an area of 9cm**2, what is the area of the circle in cm**2.
面积为9cm**2正方形内画一个最大的圆，圆的面积为多少cm**2．
<gadget id="calculator">3.14 * 2.25</gadget>
<output>7.065</output>

<result>7.065</result>