/r/ some basic trigonometry guides

so basically i know where all the hypotenuses are, but I get confused on finding the adjacent/opposites (when there's no marking on the triangles corners, etc) how do you find the adjacent/opposite of a triangle if theres no markings in the corners?
by the way: are equilateral triangles used in trig? :X

oh btw, I require url guides on saving & borrowing(prt, etc)

you HAVE to pick a corner (not the 90 angle) to be a reference point. otherwise either side could be the opposite (or adjacent). once you've decided which corner you're going to use as a reference, then trig applies.

equilateral is used, but you always split it in half and it becomes two 30-60-90 triangles, which you know each respective opposite side is in are x, 2x, x*sqrt(3).

oh I see.