First always remember that SOH CAH TOA is used for right triangles. It is used to determine unknown angles or measure of sides.
O, H, A refer to the different sides of the triangle:
H - hypotenus, the side opposite the 90º angle, also the longest of the three sides
A - adjacent, this is always the one beside the reference angle (aside from 90º)
O - opposite, the angle opposite the reference angle
Note that O and A are interchangeable depending on where the reference angle is.
S, C, T: (this should've been taught to you before sohcahtoa)
S - sine (examples: sin0 = 0 , sin 90º = 1 , sin 30º = 1/2, sin 45º = [tex] \sqrt{2} [/tex] / 2)
C- cosine (examples: cos0 =1 , cos 90º = 0 , cos 30º = [tex] \sqrt{3}[/tex] /2, cos 45º = [tex] \sqrt{2} [/tex] / 2
T - tangent (examples: tan 0 =0 , tan 90º = ∞ , tan 45º = 1)
Let x be the reference angle,
SOH: sin x = opposite /hypotenuse
CAH: cos x = adjacent /hypotenuse
TOA: tan x = opposite /adjacent
