Find `r, r', e delta` for the case shown in figure

Explanation

Here `theta = 180^(@) - 75^(@) = 105^(@)`
`sin 45^(@) = sqrt(2) sin r`
`sin 45^(@) = sqrt(2) sin r`
`:. r = sin^(-1) (1)/(2) = 30^(@)`
`r' = 180^(@) -(r + theta)`
`= 180^(@) - 30^(@) - 105^(@) = 45^(@)`
`sin e = sqrt(2) sin r'`
`:. sin e = sqrt(2) xx sin 5^(@) = 1`
`:. e = 90^(@)`
So, `delta = i + e - A = 45^(@) + 90^(@) = 6^(@)`