Question Number 176962 by HeferH last updated on 28/Sep/22
$$\:{Recommended}\:{books}\:{for}\:{trigonometry}\:{from} \\ $$$$\:{zero}?\:{I}\:{know}\:{most}\:{Euclidean}\:{geometry}, \\ $$$$\:\:{and}\:{basic}\:{algebra}.\:{I}\:{feel}\:{a}\:{bit}\:{lost} \\ $$$$\: \\ $$
Commented by TheHoneyCat last updated on 30/Sep/22
I fear there is no correct answer to your question. It really depends on what you are looking for. If you're just looking for the basic stuff (sin, cos, tan, link to the triangle) a few minutes of googling should suffice. You'd then be looking for the following keywords : "trigonometry formula", "trigonometric circle". and if you are not satisfied with the explanations some YouTube teachers or Khan Academy should suffice to get the intuition of their meaning. If you are planning on going into "hardcore trigonometry" (meaning by that, hard for highschool) what you might be looking for is actually to learn complex numbers. I know, it doesn't seem to be the same subject. But this is actually the simplest way you can PROVE the formulas I was referring to previously. All other proofs require University level math. This method will be easier than just learning those formulas (that's the nice part) but also more time consuming cause you'll have to learn complex numbers with it (that's the sad part). Again, googling stuff should be enough. Here are some keywords: "Complex numbers", "affixes", "complex numbers and geometry", "unit circle complex"... That kind of stuff. And any highschool book on complex numbers will do the trick, you don't need to be picky on it, it should be fine. Now, if you are looking to understand "everything" about trigonometry, you have to go towards what is called "power series". This is how you can get all the answers you are looking for. And you can technically understand that without complex numbers (although some books might have their knowledge as prerequisites, so mind that). Jugging by how you describe your level I really DON'T recommend this last option. But know that it exists, so if you turn out to be gifted in math, feel free to take a look. Sorry for not actually answering your question (I gave you no book name). I'm actually french so most of the books I could have recommended are probably not readable for you. I do recommend that you check Khan Academy (or other equivalents). The internet is full of good free lessons and exercises on trigonometry. Good luck to you �� in your search for knowledge (or whatever your motivation was). Hope my answer is not too disappointing.
Commented by TheHoneyCat last updated on 30/Sep/22
Oh I forgot to mention that all the things I talked about, EVEN the hardest ones DO fit your requirements, in the sense that they ONLY require Euclidean geometry and basic algebra to be understood. Don't think this it PhD Math level stuff or anything.��