Question 858028
Express the sin (-140°) as a function of a positive acute angle
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quadrant: QIII where sin is negative.
Angle:: 360-140 = 220 
Reference Angle:: 220 = 180+40
RA =  40 degrees
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sin(-140) = -sin(40)
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Cheers,
Stan H. 
1) sin 40°
2) tan 40°
3) -sin 40°
4) -tan 40°