A rope can be used to form a rectangle with a length of 11 cm and a width of 7 cm. If this rope is used to form a square, what is the side length of the square?
用一根绳子能围成一个长11厘米、宽7厘米的长方形，如果把这根绳子围成一个正方形，这个正方形的边长是多少？
<gadget id="calculator">11 + 7</gadget>
<output>18</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">18 * (1/2)</gadget>
<output>9</output>

<result>9</result>