The Y or imag. axis cuts it dead center......vertically.......the x axis horizontally.........the two inner green points.............are the 1/2 in either direction along the X axis...............one unit apart........they form the base of the top equil triangle....................of sides of 1.............a smaller one.........b/c the lines intersecting it are parellel......the angles are also 60 degrees...................if u split that triangle in half.......along the Y axis......................u have two right triangles.............30/60 type..........of hyp of 1.......and base of 1/2......which means the side along the Y axis is the square root of 3 divided by 2.............from tip to bottom....is the square root of 3........the same as the major axis for the ellipse...............the horizontal axis, minor axis is one......the distance between the two center green points below...................