Draw the largest circle in a square with an area of 20 square centimeters. What is the area of the circle?
在面积为20平方厘米的正方形内画一个最大的圆，圆的面积是多少？
<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>