[antod]

Since high school in the 80s I still remember the phonetic mnemonic "soh cah toa" one teacher mentioned off the cuff once.

sine is opposite over hypotenuse

cosine is adjacent over hypotenuse

tangent is opposite over adjacent

[peterfirefly]

The unit circle diagram is nicer because it naturally works with angles bigger than 180 and negative angles. If you look at the unit circle with a radius and the intersection point with the circle, you naturally get a right triangle of the kind your mnemonics apply to.

It also has the advantages of being language/culture blind.