A piece of iron wire with a length of 15 cm is made into an isosceles triangle with a waist length of 6 cm. What is the length of its base in cm?
把一根长15厘米的铁丝做成一个腰长6厘米的等腰三角形，它的底边长是多少厘米？
<gadget id="calculator">15 - 6 - 6</gadget>
<output>3</output>

<result>3</result>