Then, AE = v2 t
and CE would represent the refracted wavefront If we
now consider the triangles ABC and AEC, we readily
obtain
sin i = 
1
BC
AC
AC
=v τ
(10 1)
and
sin r = 
2
AE
AC
AC
=v τ
(10 2)
where i and r are the angles of incidence and refraction,
respectively