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Question: General solution of the equation \(2\cos^{2}\theta - (\sqrt{2} + 1)\cos\theta - 1 + \frac{(\sqrt{2} ...

General solution of the equation 2cos2θ(2+1)cosθ1+(2+1)2=02\cos^{2}\theta - (\sqrt{2} + 1)\cos\theta - 1 + \frac{(\sqrt{2} + 1)}{\sqrt{2}} = 0is.

A

\Rightarrow

B

cosθ=(2+1)±(2+1)2824\cos\theta = \frac{(\sqrt{2} + 1) \pm \sqrt{(\sqrt{2} + 1)^{2} - \frac{8}{\sqrt{2}}}}{4}

C

\Rightarrow

D

None of these

Answer

cosθ=(2+1)±(2+1)2824\cos\theta = \frac{(\sqrt{2} + 1) \pm \sqrt{(\sqrt{2} + 1)^{2} - \frac{8}{\sqrt{2}}}}{4}

Explanation

Solution

On simplification, it reduces to

\Rightarrow

θ=2nπ±π3\theta = 2n\pi \pm \frac{\pi}{3} 2secθ+tanθ=12cosθ+sinθcosθ=1\sqrt{2}\sec\theta + \tan\theta = 1 \Rightarrow \frac{\sqrt{2}}{\cos\theta} + \frac{\sin\theta}{\cos\theta} = 1.