In math class, Mr. Li used a wire to form a rectangle with a length of 9 cm and a width of 3 cm. A square is formed by another wire of the same length. What is the side length of this square?
上数学课时，李老师用一根铁丝围成一个长9厘米，宽3厘米的长方形．用另一根同样长的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">9 + 3</gadget>
<output>12</output>

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

<gadget id="calculator">12 * (1/2)</gadget>
<output>6</output>

<result>6</result>