Question : Simplify $\frac{\cos ^4 \theta-\sin ^4 \theta}{\sin ^2 \theta}$.
Option 1: $1-\tan ^2 \theta$
Option 2: $\tan ^2 \theta-1$
Option 3: $\cot ^2 \theta-1$
Option 4: $1-\cot ^2 \theta$
Correct Answer: $\cot ^2 \theta-1$
Solution : $\frac{\cos ^4 \theta-\sin ^4 \theta}{\sin ^2 \theta}$ $= \frac{(\cos^2 \theta - \sin^2 \theta)(\cos^2 \theta + \sin^2 \theta)}{\sin ^2 \theta}$ $=\frac{\cos^2 \theta - \sin^2 \theta}{\sin ^2 \theta}$ [As $\cos^2 \theta + \sin^2 \theta = 1$] $=\frac{\cos^2 \theta}{\sin ^2 \theta}-\frac{\sin^2 \theta}{\sin^2 \theta}$ $=\cot ^2 \theta-1$ Hence, the correct answer is $\cot ^2 \theta-1$.
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Question : Simplify. $\frac{\sin8\theta \cos\theta - \sin6\theta \cos3\theta}{\cos2\theta \cos\theta - \sin3\theta \sin4\theta}$
Option 1: $\cot \theta$
Option 2: $\cot 2 \theta$
Option 3: $\tan \theta$
Option 4: $\tan 2 \theta$
Question : The value of $\frac{2 \cos ^3 \theta-\cos \theta}{\sin \theta-2 \sin ^3 \theta}$ is:
Option 1: $\sec \theta$
Option 2: $\sin \theta$
Option 3: $\cot \theta$
Option 4: $\tan \theta$
Question : If $\cos ^2 \theta-\sin ^2 \theta=\tan ^2 \phi$, then which of the following is true?
Option 1: $\cos \theta \cos \phi=1$
Option 2: $\cos ^2 \phi-\sin ^2 \phi=\tan ^2 \theta$
Option 3: $\cos ^2 \phi-\sin ^2 \phi=\cot ^2 \theta$
Option 4: $\cos \theta \cos \phi=\sqrt{2}$
Question : $\sqrt{\frac{1+\sin\theta}{1-\sin\theta}}+\sqrt{\frac{1-\sin\theta}{1+\sin\theta}}$ is equal to:
Option 1: $2\cos\theta$
Option 2: $2\sin\theta$
Option 3: $2\cot\theta$
Option 4: $2\sec\theta$
Question : If $\frac{\tan\theta +\cot\theta }{\tan\theta -\cot\theta }=2, (0\leq \theta \leq 90^{0})$, then the value of $\sin\theta$ is:
Option 1: $\frac{2}{\sqrt3}$
Option 2: $\frac{\sqrt3}{2}$
Option 3: $\frac{1}{2}$
Option 4: $1$
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