Question 9954: Given the following, evaluate cos
cos= 1/2
tan is negative?
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! i am assuming i have understood your stripped down version of the question... Also look into my Lesson of Trig equations, as the explanation is there, more than what i will explain here.
Let angle be A, so cosA=1/2...what is the angle if tanA is negative.
Well, from your calculator, angle A is 60 degrees but if we do tan60, we get a positive angle.
Question is, where is cos +ve but tan -ve? Answer is the 4th quadrant, so the angle we require is actually 300 degrees...
cos300 --> +1/2
tan300 is -ve
jon.
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