The refractive index of the material of a thin prism is equal to? ('A' is angle of the prism and 'Dm' is angle of minimum deviation)

The refractive index of the material of a thin prism is equal to? ('A'

1.	The refractive index of the material of a thin prism is equal to? ('A' is angle of the prism and 'Dm' is angle of minimum deviation)
A.	1 + Dm/A
B.	1 - Dm/A
C.	1 + A/Dm
D.	1 - A/Dm
Answer» B. 1 - Dm/A