I've drifted off course! help....

[Gillespie]

Hi,

Given; Distance 'A' to 'B' is 90nm, a fix is obtained 60nm along and 4nm to the right of course. what heading alteration must be made to reach 'B'?

I can work this out using trig, but this is abviously far too clumsy to work in the air, what is the quickest way to calculate this. What is the '1 in 60' rule.

Thanks.