# question on determining values of an angle where the tangent is a certain value

How would I solve this question?

Determine the values of $\theta \in [0,2\pi]$ for which $\tan\theta = -\sqrt{\sec^2{\theta} - 1}$ is true.

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What have you tried? –  wckronholm May 14 '11 at 20:46

Hint 1: It will not be true if $\tan \theta \gt 0$

Hint 2: $\sec \theta = 1/ \cos \theta$

Hint 3: $\sin^2 \theta + \cos^2 \theta =1$

Hint 4: $\tan \theta = \sin \theta / \cos \theta$

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+1. Thanks for pointing out the error in my first solution. –  Américo Tavares May 14 '11 at 23:38