The direction vector of the vertical line of the straight line is (0, 1,-1) × (1, 0) = (0, 1,-1).

The equation perpendicular to the plane z = 0, that is, perpendicular to the xOy plane, is set to Ax+By+D = 0,

If the plane intersects the vertical line, the normal vector is perpendicular to the vertical direction vector, and -B = 0.

If the plane passes through (1,-1, 1), then A-B+D = 0.

The simultaneous solution is B = 0 and D = -A a a.

The plane equation is Ax-A = 0 and x = 1.