I really wish they'd put a class like that right after basic symbolic algebra in normal school curriculum - it's far more useful in the modern world than trigonometry.
Otherwise these rules come out as a set of vague half-instructions that always lead to rounds of revisions in UAT. Oh, and "we only scheduled a week of UAT".
A broader knowledge of discreet theory would be much more helpful than understanding a sine or cosine at a... trigonometric level.
It's incredibly well-written. Very challenging, yet totally approachable and accessible to someone with even just a rather basic (even foggy) understanding of "high-school" math.
I, quite a few times, spent more than four hours with a pencil and paper making my way through 2-4 pages of material, as since my background was lacking, there were parts where I had to figure out how they got from A to B. IIRC, I spent multiple days on a few paragraphs at one point.
That said, it is written how I think math books should be written, is considered part of the start of Discrete Mathematics, and is conversational, illuminating, well-layed-out, and approachable despite it's level of difficulty.
I can't recommend it enough.
Don't view it as something where if you're not making progress you're failing. Take the time to ensure you understand every bit of what you read before moving on, and do all the exercises you can muster.
But anyway, the Teaching Company offers a phenomenal course on Discrete Math, taught by none other than the "Math Magician" Arthur Benjamin (seriously, this guy is magic. He can do 5 digit squares in his head!). It's easily torrent-able / available through more traditional means.