Hope this makes sense.
Q1. Parallel of origin is where convergence is correct.
Constant of cone = sin parallel of origin
inv sin 0.3955 = 23.2971 = answer b
Q2. Convergence = ch long x sin parallel of origin(constant of cone)
Sin parallel of origin = convergence/ch long = 30/40 = 0.75
answer b
Q3. 3nm off track at 30nm = 6 degree track error relative to start
3nm off track at 90nm = 2 degree track error relative to destination
If track error is measured from both ends simultaneously then alteration toward destination by sum of track errors is the way ahead which is 8 degrees R, answer d.
If track error is measured relative to destination then alter towards heading by amount of error, this would be 2 degrees R but that is not given as an answer.
If track error is measured from start then alter heading by twice the error which would be 12 degrees R, also not given.
I think is right, any other explanations would help me also.
Noz