Show that for a light ray incident at an angle i on getting reflected the angle of deviation is `delta=pi-2i` or `pi +2i`.

Explanation

From Fig. it is clear that light ray bends either by `delta_1` anticlockwise or by `delta_2(= 2pi-delta_1)` clockwise.
From Fig.
`delta_1=pi-2i.`
`:. delta_2=2pi-(pi-2i)=pi+2i`