How is lateral displacement (reflection/refraction) derived?

[zell_D]

my book is only introductory and they only gave me the equation S = t*sin( theta1 -theta2)/cos(theta2), i like to know how its derived so i can better understand and memorize this... i know i can probably work this out myself but i don't know where to start

i am assuming it has something to do with snells law and trig, but I am bad at those

 

[darkchild]

Lateral displacement of what, exactly? It might help if you tell us what the the variables stand for.

 

[zell_D]

when light goes from a less dense media to a more dense media (air to glass), it is refracted. if its a glass slab, it will be refracted again as it exits the slab. S = lateral displacement of the incidence ray. t = the width of the slab, theta 1 is the angle of incidence while theta 2 is the angle of refraction