Draw a circle with the radius of any side of the square, and the area of the square is 5 square centimeters, what is the area of the circle in square centimeters?
以正方形的任何一条边长为半径画一个圆，已知正方形的面积为5平方厘米，那么这个圆的面积是多少平方厘米．
<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>