\(n=\frac{sin\frac{A+\delta_{min}}{2}}{sin\frac{A}{2}}=\frac{sin(30+\frac{\delta_m}{2})}{sin(30)}\)

\(\delta_m=2sin^{-1}(\frac{n}{2})-60\)

for \(n_{red}=1.525\)

\(\delta_m=2sin^{-1}(\frac{1.525}{2})-60=39.37^0\)

for \(n_{blue}=1.535\)

\(\delta_m=2sin^{-1}(\frac{1.535}{2})-60=40.26^0\)

\(\delta_{m,blue}-\delta_{m,red}=40.26^0-39.37^0=0.89^0\)