Complex numbers A level question

In an Argand diagram, the vertices of an equilateral triangle lie on a circle with centre at the origin. One of the vertices represents the complex number 4 + 2i. Find the complex numbers represented by the other two vertices. Give your answers in the form x + iy, where x and y are real and exact.
I have no idea how to solve this.
I tried doing this:

4+2i
√(4^2 + 2^2)
r= 2√5
tan ^-1 = 2/4
θ= 26.565

I also know that the three points are the same distance from the origin and separated by equal angle of 120.

But I don't know what to do from here.
Help