The index of refraction for violet light in silica flint glass is 1.66, and that for red

Question:

The index of refraction for violet light in silica flint glass is 1.66, and that for red light is 1.62. What is the angular dispersion of visible light passing through a prism of apex angle 60.0° if the angle of incidence is 50.0°?

$The index of refraction for violet$