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3 votes
Which expression is equivalent to cos120°?

User Eric Wang
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2 Answers

4 votes
Cos 120 degrees has a reference angle of 60 degrees and it is located in Quadrant II.
Since the reference angle is 60 degrees it will have the same cos as 60 degrees in Q I. Cos 60 = 1/2
In Q II cos is negative so Cos 120 = -1/2
User Vishwa Ratna
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8.0k points
3 votes
-1/2,3/2 or 2pie/3 because thats how it is on the unit circle
User Trace
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