An equilateral triangle with side length 10 decimeters can be formed by a rope. If this rope is used to form an isosceles triangle whose base length is 8 decimeters, how many decimeters is the length of one side of this isosceles triangle?
有一根绳子正好可以围成一个边长10分米的等边三角形．如果用这根绳子围成一个底边长为8分米的等腰三角形，那么这个等腰三角形的一腰长为多少分米？
<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">30 - 8</gadget>
<output>22</output>

<gadget id="calculator">22 / 2</gadget>
<output>11</output>

<result>11</result>