Question

If $\tan \frac{\theta}{2}=\operatorname{cosec} \theta-\sin \theta$, then -

• A. $\sin ^2 \frac{\theta}{2}=2 \sin ^2 18^{\circ}$
• B. $\cos 2 \theta+2 \cos \theta+1=0$
• C. $\sin ^2 \frac{\theta}{2}=4 \sin ^2 18^{\circ}$
• D. $\cos 2 \theta+2 \cos \theta-1=0$

Answer 1

Answer: (A), (D)

Correct answer is (a) $\sin ^2 \frac{\theta}{2}=2 \sin ^2 18^{\circ}$Correct answer is (d) $\cos 2 \theta+2 \cos \theta-1=0$