A wire encloses a square with a side length of 15.7 centimeters. If it encloses a circle with the largest area, what is the circumference of the circle in centimeters?
一根铁丝正好围成一个边长是15.7厘米的正方形，若把它围成一个面积最大的圆形，圆形的周长是多少厘米．
<gadget id="calculator">15.7 * 4</gadget>
<output>62.8</output>

<result>62.8</result>