Because it is an isosceles triangle, ab may be equal to ac or Bc. Suppose ab=ac, ab:ac:bc is 1: 1:2. It can be calculated that ab=ac=4.5 and bc=9. According to the nature and summation of triangles, none of these three sides can be triangles, so they are omitted. Suppose ac=bc, then ac:ab:bc is 2: 1:2, calculate ac=bc=7.2, then ab is 3.6, and then according to the nature of the triangle, we can know that these three sides can form a triangle row. So ac=bc=7.2, ab=3.6. I hope to adopt pure mobile phone typing, but I don't know how to ask again.