The perimeter of a square is equal to the perimeter of a circle. It is known that the side length of the square is 31.4 cm. What is the perimeter of the circle?
一个正方形的周长与一个圆的周长相等，已知正方形的边长是31.4厘米，那么圆的周长是多少．
<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>