In an isosceles triangle, if the vertex angle is twice the sum of the base angles, then the angles of the triangle are
120o, 30o, 30o
Let the base angles be x and x.
Then, vertical angle = 4x.
Now, x + x + 4x = 180° (angle sum property of a triangle)
therefore x = 30°
Hence, angles of the triangle are 120°, 30°, 30°.