Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror and parallel to the second is reflected from the second mirror parallel to the first mirror. Determine the angle between the two mirrors.
Let be the angle between the two mirrors
and
. The incident ray
is parallel to mirror
and strikes the mirror
at an angle of incidence equal to
. From figure we have
Similarly for reflection at mirror , we have
Now in triangle , therefore