An equilateral prism deviates a ray through `45^(@)` for the two angles of incidence differing by `20^(@)`. The angle of incidence is

Options

A. `62.5^(@)`
B. `42.5^(@)`
C. Both are correct
D. Both are wrong

Explanation

We have, `delta=i_(1)+i_(2)-A`
`45^(@)=(i_(1)+i_(2))-60^(@)`
`therefore i_(1)+i_(2)=105^(@)" ...(i)"`
and `i_(1)-i_(2)=20^(@)" ...(ii)"`
On solving Eqs. (i) and (ii), we get
`i_(1)=62.5^(@) and i_(2)=42.5^(@)`