The trig functions of the trigonometric unit circle are negative at the following quadrants
Quadrant I: there's no negative function;
Quadrant II: cosine, tangent, cotantent, and secant are negatives;
Quadrant III: sine, cosine, secant and cosecant are negatives; and
Quadrant IV: sine, tangent, cotangent, and cosecant are negatives.
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