(b) Given that, $\tan{\theta = \sqrt{3} = \tan{\frac{\pi}{3}\ \Rightarrow \ \theta = n\pi + \frac{\pi}{3}}}$ For $–\pi < \theta < 0\ put\ n = - 1,$ we get $\theta = - \pi + \frac{\pi}{3} = \frac{- 2\pi}{3}\ or\ \frac{- 4\pi}{6}$
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