Yes, this was what confused me initially. I did not know you were talking about intervals and assumed them to be points on the xy plane, not in the manner (x,y) because that would mean y was 90, but in the way that you were considering 0-90 or simply 90 and within the entire restriction [0,360]. My bad.Are you confused by the difference between the notation for an interval, which looks like [0,90], and consists of all the real numbers between and including 0 and 90; versus the notation for a point in the xy plane, which looks like (4,5), and indicates the point where x = 4 and y = 5?
Well, you just said earlier that we have to state the largest value of A, and I forgot that the question also asked this so I would have to say that [0,90] is better simply because it is a larger interval than [0,45] and has a larger continuum. Or that 90 is also written as pi/2 and 45 as pi/4 so pi/2, being the larger value of the two, is chosen.Getting back to the problem: g is one-to-one on the interval [0,45], and g is one-to-one on the interval [0,90]. So why is A = 90 the best answer to your problem?
Could this be it?