Question

If $\cos\theta = \frac{- 1}{2} = \cos\frac{2\pi}{3}$, then the general value of $\theta = 2m\pi \pm \frac{2\pi}{3}$ is .

• A. $2\sqrt{3}\cos^{2}\theta = \sin\theta$
• B. $2\sqrt{3}\sin^{2}\theta + \sin\theta - 2\sqrt{3} = 0$
• C. $\sin\theta = \frac{- 1 \pm 7}{4\sqrt{3}} \Rightarrow \sin\theta = \frac{- 8}{4\sqrt{3}},$
• D. $\sin\theta = \frac{6}{4\sqrt{3}} = \frac{\sqrt{3}}{2}$

Answer 1

Answer: (B)

$2\sqrt{3}\sin^{2}\theta + \sin\theta - 2\sqrt{3} = 0$

Answer 2

$A = n\pi + \frac{\pi}{4}$

$\tan\theta + \frac{1}{\tan\theta} = 2 \Rightarrow$.