The perimeter of an isosceles triangle is 66 cm, its base is 24 cm, what is its waist length in cm?
一个等腰三角形的周长是66cm，它的底边长是24cm，它的腰长是多少厘米？
<gadget id="calculator">66 - 24</gadget>
<output>42</output>

<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<result>21</result>