I’m probably way too elementary for this post, but just in case someone doesn’t know about SohCahToa (pro. soh-cah-toh-ah).
Soh
sin is opposite over hypotenuse
Cah
cos is adjacent over hypotenuse
Toa
tan is opposite over adjacent
I made it through my college trigonometry class by just remembering that one simple pneumonic. Everything else that was taught could be derived from it.