Assume that light is incident normal to the surface of a film of thickness ddd. How much farther does the light reflected from the back surface travel than the light reflected from the front surface

Find the equation for the plane through upper p 0 left parenthesis negative 4 comma negative 8 comma negative 5 right parenthesis perpendicular to the following line. xequalsnegative 4 minus t, yequalsnegative 8 plus 2 t, zequals3 t, minusinfinityless thantless thaninfinity