A circle with a diameter of 12 cm can be enclosed by a piece of iron wire. If it is used to enclose a square, what is the side length of the square?
用一根铁丝可围成直径是12厘米的圆，如果用它围成正方形，则正方形的边长是多少？
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<result>9.42</result>