An isosceles triangle and a square have the same perimeter. The side length of the square is 9 cm. The length of the base of the isosceles triangle is 16 cm. What is the length of its waist in cm?
一个等腰三角形和一个正方形的周长相等，正方形的边长是9厘米，等腰三角形的底边长是16厘米，它的腰长多少厘米．
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<gadget id="calculator">36 - 16</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>