The `x-y` plane is the boundary between two transparent media. Medium-`1` with `z gt0` has refractive index `sqrt2` and medium `-2` with `zlt 0` has a refractive index `sqrt3`. `A` ray of light in medium `-1` given by the vector `A=6sqrt3 i+8sqrt3j-10k` is incident on the plane of separation. If the unit vector in the direction of refracted ray in medium `-2` is `(1)/(5) (ai+bj-(5)/(sqrt2)k)` then the value of ab.