A rectangle with a length of 11 centimeters and a width of 7 centimeters is exactly surrounded by a piece of iron wire. If this iron wire is used to form a square, what is the side length of the square in centimeters?
用一根铁丝正好围成一个长11厘米，宽7厘米的长方形，如果用这根铁丝围成一个正方形，这个正方形的边长是多少厘米
<gadget id="calculator">11 + 7</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<result>9</result>