The radius of the large circle is equivalent to the diameter of the small circle. It is known that the area of the large circle is 9.42 square decimeters larger than that of the small circle. What is the area of the large circle in square decimeters?
大圆的半径相当于小圆的直径，已知大圆面积比小圆面积多9.42平方分米，大圆的面积是多少平方分米．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">9.42 / 3</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>