Given that the radius of the circle is equal to the side length of the square, and the area of the square is 10 square decimeters, what is the area of the circle in square decimeters?
已知圆的半径等于正方形的边长，正方形的面积是10平方分米，求圆的面积是多少平方分米？
<gadget id="calculator">3.14 * 10</gadget>
<output>31.4</output>

<result>31.4</result>