The SLANTING line also has to move since the SLANTING line is drawn with reference to X-axis and Y-axis to begin with, isn’t it? So, assuming the line is 45 degree slanting, the (x,y) values would be (1,1)(2,2)(3,3)(4,4) … etc. If the X and Y co-ordinates are rotated and if the SLANTING line is redrawn with the previous values it would still be a SLANTING line.
Obviously, looks like I’m missing something. Also, could you refer me to a book that I can read and understand better?