Question : The greatest value of $\sin ^{4 }\theta +\cos ^{4}\theta$ is:
Option 1: $2$
Option 2: $3$
Option 3: $\frac{1}{2}$
Option 4: $1$
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Correct Answer: $1$
Solution : To find the maximum value of $\sin^4\theta +\cos^4\theta$ We can write this expression as, $\sin^4\theta +\cos^4\theta=(\sin^2\theta)^2 +(\cos^2\theta)^2 +2\sin^2\theta \cos^2\theta- 2\sin^2\theta \cos^2\theta$ $=(\sin^2\theta+\cos^2\theta)^2- 2\sin^2\theta \cos^2\theta = 1-2\sin^2\theta \cos^2\theta$ $= 1-\frac{(\sin^22\theta)}{2}$ For the maximum value of the above function, $\frac{(\sin^22\theta)}{2}$ should have minimum value, i.e., 0. So, Maximum Value = 1 Hence, the correct answer is $1$.
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Question : What is the value of $\frac{\sin \theta+\cos \theta}{\sin \theta-\cos \theta}+\frac{\sin \theta-\cos \theta}{\sin \theta+\cos \theta}$?
Option 1: $\frac{1}{\left(\sin ^2 \theta-\cos ^2 \theta\right)}$
Option 2: $2\left(\sin ^2 \theta-\cos ^2 \theta\right)$
Option 3: $\frac{2}{\left(\sin ^2 \theta-\cos ^2 \theta\right)}$
Option 4: $\sin ^2 \theta-\cos ^2 \theta$
Question : If $\frac{\sin\theta+\cos\theta}{\sin\theta-\cos\theta}=3$, then the value of $\sin^{4}\theta$ is:
Option 1: $\frac{2}{5}$
Option 2: $\frac{1}{5}$
Option 3: $\frac{16}{25}$
Option 4: $\frac{3}{5}$
Question : The value of $\frac{\sin\theta-2\sin^{3}\theta}{2\cos^{3}\theta-\cos\theta}$ is equal to:
Option 1: $\sin\theta$
Option 2: $\cos\theta$
Option 3: $\tan\theta$
Option 4: $\cot\theta$
Question : If $\sin \theta \cos \theta=\frac{1}{\sqrt{3}}$ then the value of $\left(\sin ^4 \theta+\cos ^4 \theta\right)$ is:
Option 1: $1$
Option 2: $\frac{5}{3}$
Option 3: $\frac{2}{3}$
Option 4: $\frac{1}{3}$
Question : If $\sin \theta \cos \theta=\frac{\sqrt{2}}{3}$,then the value of $\left(\sin ^6 \theta+\cos ^6 \theta\right)$ is:
Option 1: $\frac{1}{3}$
Option 2: $\frac{4}{3}$
Option 4: $\frac{5}{3}$
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