SOLUTION: what is the value of theta in the interval [0 degrees,360 degrees)that have given function value cos=-1/2

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Question 563830: what is the value of theta in the interval [0 degrees,360 degrees)that have given function value
cos=-1/2
Found 2 solutions by josmiceli, richard1234:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
What is theta when cos = -(1/2) ?
Theta can't be the 1st quadrant or
the 4th quadrant because cos is
always (+) there.
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In the 2nd quadrant, +cos%28+120+%29+=+-%281%2F2%29+
This angle is 180 - 60
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In the 3rd quadrant, +cos%28+240+%29+=+-%281%2F2%29+
This angle is 180 + 60
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Theta is 120 and 240 degrees

Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Cosine of what equals -1/2? Theta? 2*theta? If it is theta, follow the other tutor's solution. If not, set the argument of the cosine function equal to 120 or 240 or any other number x such that cos(x) = -1/2.