Angle of incidence when it is twice the angle of refraction, in terms of refractive index

1. A.
   $\cos^{-1}\!\left(\frac{\mu}{2}\right)$
2. B.
   $2\cos^{-1}\!\left(\frac{\mu}{2}\right)$
3. C.
   $\sin^{-1}\!\left(\frac{\mu}{2}\right)$
4. D.
   $2\sin^{-1}\!\left(\frac{\mu}{2}\right)$

Tap an option to check your answer.

1. A.
   $\sin^{-1}\left(\dfrac{n}{2}\right)$
2. B.
   $2\cos^{-1}\left(\dfrac{n}{2}\right)$
3. C.
   $2\sin^{-1}\left(\dfrac{n}{2}\right)$
4. D.
   $\cos^{-1}\left(\dfrac{n}{2}\right)$

Tap an option to check your answer.