A piece of iron wire forms a square with a side length of 15 centimeters. If the iron wire is changed into an equilateral triangle, what is the side length in centimeters?
一条铁丝围成正方形，边长15厘米，如果把这条铁丝改围成正三角形，边长是多少厘米？
<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">15 * (4/3)</gadget>
<output>20</output>

<result>20</result>