If the waist length of the isosceles triangle ABC is 3cm and the vertex angle is 120 degrees, the diameter of its circumscribed circle is

If the waist length of the isosceles triangle ABC is 3cm and the vertex angle is 120 degrees, the diameter of its circumscribed circle is


The results show that: 1. The base is 3-178; + 3-178; - 2.3.3cos 120 ° = 27
Bottom = 3 √ 3
½ diameter = 3 √ 3 / sin120 ° = 6
Ψ diameter = 12