Use the unit circle to find the 6 trig. functions for the angle 150 and 210

What angle do you use? The reference angle would be 30 degrees in both cases, so can I use 30 degrees? Or is it in one case negative? Please help me, thanks

The key is to look at the Quadrants the angles lie in. All you have to do is logically switch the signs of the coordinates of the point at which the reference angles cross the unit circle.
A reference angle in Quadrant I hits the circle at point (u,v). The angles in other quadrants which reference the original angle will follow this pattern: Quadrant II (-u,v) ; Quadrant III (-u,-v); Quadrant IV (u,-v). You use these points to find the six trig functions very easily.