ok but am really confused
ok what u do is place your protractor on the wavefront in air mark and draw 90* do the same for wavefront in the glass ..
then on the edge of the glass mark and draw 90* you'll get the Normal
y draw normal later .. because u get the specific position of both the incident and the refracted ray at that point and you HAVE to hav the normal on the point
is rays can be ANYWHERE as long as they are 90* pr perpendicular to the wavefront
