I have 2 vertices and I want to make circle, that those 2 vertices are reference points of the circle.

I know that one of the vertices (right one on picture) is center of circle horisontally.

So I have to know where is center of the circle and after that I just use spin tool.

Do you have any fast and easy way to do it ?

My way is:

Select right one vertice and extrude it down as far you like

Select both reference(original) vertices

Cursor to selected

Spin: steps 4 (to get 90 degrees angle)

Pivot point to cursor

Select one new vertex and scale it over middle edge (which I made first)

Select 2 crossing edges

Edges X intersection (addon)

Intersection point is middle point of circle