Min Zichen surrounded a triangle with three copper wires. The length of the first root is 11 cm, the length of the second root is 5 cm, and the length of the third root can form an isosceles triangle.
闵子辰同学用三根铜丝围一个三角形．第一根长11厘米，第二根长5厘米，第三根长多少厘米才能围成一个等腰三角形．
<result>11</result>