The Y-Z plane separates two media A and B of refractive indices μ1=1.5 and μ2=2.  A ray of light travels from A to B. Its directions in two media are given by unit vectors u1→=ai^  + bj^   and u2→= ci^  + d j^  Then

as the light rays are falling on the yz plane X axis is perpendicular to the plane. then angle or incidence with X axis tan i will be ba and sin i  will be ba2+b2=b smilarly sinr= dc2+d2 =d  as U1 and U2 are unit vectors a2+b2=c2+d2=1 according to Snell's law  μ1sini =μ2sin r                                           32b=2d   bd=43