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How do you find $cos x = - \frac{1}{2}$ $cos x= -1/2$ ?

1 Answer

Aug 14, 2015

cos x = - 1/2 = cos 2 $π$ $pi$ /3 $\Rightarrow$ $=>$ x = 2 $π$ $pi$ /3

Explanation:

Cosine negative in the second quadrant. cos $π$ $pi$ /3 = 1/2.
cos ( $π$ $pi$ - $θ$ $theta$ )= - cos $θ$ $theta$

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