Draw a largest square inside a circle, the diagonal length of the square is 12 cm, what is the circumference of the circle in cm?
在一个圆内画一个最大的正方形，正方形对角线长12厘米，圆的周长是多少厘米．
<gadget id="calculator">3.14 * 12</gadget>
<output>37.68</output>

<result>37.68</result>