Use a 20cm long string to form an isosceles triangle. If the base is 8cm, what is the waist in centimeters?
用一根20cm长的细绳围成等腰三角形，如果底是8cm，那么腰是多少厘米？
<gadget id="calculator">20 - 8</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>