SOLUTION: what is the exact value of cos120 degreees?

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Question 197033: what is the exact value of cos120 degreees?
Answer by anantha(86) About Me  (Show Source):
You can put this solution on YOUR website!
sol:
cos120=cos(180-60)
=-cos(60) (i.e;cos(180-thita)= -cos(thita))
=- 1/2 (cos60=1/2)
=-0.5