The CAST Rule describes the sign of the three primary trigonometric ratios as the angle varies from 0° to 360°. Describe how the CAST Rule relates to the behavior of the graphs of each of y = sin(x), y = cos(x) and y = tan(x).
I use the pneumonic device: All Students Take Calculus
Starting in quadrant I, where all the trig functions are positive, moving counter-clockwise. So in Quadrant II, sin values are positive, Q III tangent values are positive, Q IV cosine values are positive.
Is this what you were trying to figure out?