Solve question 40

40.  A monochromatic beam of light is incident at 60$°$ on one face of an equilateral prism of refractive intex n and emerges from the opposite face making an angle $\theta$(n) with the normal (see the figure). For n = $\sqrt{3}$ the value of $\theta$ is 60$°$ and $\frac{d\theta }{dn} = m.$The value of m is                                         [JEE Advane - 2015]