These
plane waves satisfy the dispersion relations, kx2+
kz2
= k12,
krx2+
krz2
= k12,
ktx2+
ktz2
= k22
, kx
= k1
sin θi,
krx
= k1
sin θr,
and ktx
= k2
sin θt.
The condition kx
= krx
implies that θr
= θi,
namely, the angle of reflection is equal to the angle of incidence.
