A piece of iron wire can be folded into a rectangle with a length of 4.5 meters and a width of 3 meters. If it is folded into an equilateral triangle, what is the side length of the equilateral triangle?
一根铁丝可以折成一个长4.5米，宽3米的长方形，如果用它折成一个等边三角形，那么这个等边三角形的边长是多少米．
<gadget id="calculator">4.5 + 3</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 * 2</gadget>
<output>15</output>

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<result>5</result>