The side length of a square is equal to the radius of the circle. If the area of the square is 20 square meters, what is the area of the circle in square meters?
一个正方形的边长和圆的半径相等，已知正方形的面积是20平方米，圆的面积是多少平方米．
<gadget id="calculator">20 * 3.14</gadget>
<output>62.8</output>

<result>62.8</result>