Here are some useful tips
(S)OH (C)AH (T)OA:
O = Opposite, A = Adjacent, H = Hypotenuse
Sin = O/H , Cos = A/H, Tan = O/A
Csc = H/O , Sec = H/A, Cot = A/O
SOH stands for Sine equals Opposite over Hypotenuse.
CAH stands for Cosine equals Adjacent over Hypotenuse.
TOA stands for Tangent equals Opposite over Adjacent.
To determine where SIN, COS, or TAN positive or negative:
Remember this (ASTC) * (A)ll (S)tudents (T)ake (C)alculus *
Quadrant I = (A)ll meaning all of trig functions are positive
Quadrant II = (S)tudents meaning only Sine is positive(hint the S)
Quadrant III = (T)ake meaning only Tangent is positive(hint the T)
Quadrant IIII= (C)alculus meaning only Cosine is positive(hint the C)
These are for memorization. memorization is not the best technique in mathematics