Making objects spawn/appear in a triangle formation

i know there is math involved and i want to learn more and want to use math to do it.
Oh btw the triangle formation is like the pool game/snooker triangle formation
Sorry im new here and i think this is how you tag someone @Bunny83

Something like this:

public int rows = 4;
public float size = 1f;

void SpawnObjects()
{
    float sin60 = Mathf.Sin(Mathf.Pi/3f);
    for(int y = 0; y < rows; y++)
    {
        for(int x = 0; x < y+1; x++)
        {
            var pos = new Vector2((x-y*0.5f)*size, y*size*sin60);
            // Instantiate(obj, pos, Quaternion.identity);
        }
    }
}