#154 overall
Trigonometry
Khan Academy
3 recommenders · 3 threads · recommended in 3 years, 2013–2026 · score 2.8
Khan Academy's free trigonometry course, a self-paced series of video lessons and practice exercises covering angles, trig functions, identities, and their applications. It is one part of Khan's broader math curriculum.
Commenters call it the go-to resource for reviewing trig and say they can vouch for its quality.
Recommendations by year
20062026
For this partcular purpose, look no further thank Khan Academy.
I recommended a lot of people these courses and myself went over a few videos to revise Trigonometry.
I can vouch for the quality.
Since I'm between jobs, I've been taking the time to relearn geometry, trig, calc, and linear algebra. I've finished the first two and it's both humiliating and really fun to relearn some math. As an adult, I feel a very different appreciation for how much fundamental math we take for granted. I definitely recommend https://www.khanacademy.org/ and pauls notes (https://tutorial.math.lamar.edu/).
Calculus gets a bad rap for being difficult, but if you're learning on your own, you can just focus on the ideas and not on the arduous computation (which something like maxima can do for you). The core ideas of calculus can probably be learned in a week. Review all the trig on Khan Academy, then try watching some calculus lectures, focusing on the big ideas, not memorizing rules for computing derivatives or integrals.
BTW, you probably don't need much calculus to learn most of the linear algebra you need; those requirements are mostly there for mathematical maturity, plus then being able to assign more interesting exercises.