In a circle, make a square with its radius as the side length. It is known that the area of the square is 16 square centimeters. What is the area of the circle in square centimeters?
在一个圆内，以它的半径为边长做一个正方形，已知正方形的面积是16平方厘米，圆的面积是多少平方厘米．
<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>