CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2000

  • question_answer
    If \[2\sec 2\alpha =\tan \beta +\cot \beta ,\] then one the value of \[(\alpha +\beta )\] is:

    A)  \[\pi /4\]                            

    B)  \[\pi /2\]

    C)  \[\pi \]                                

    D)  \[2\pi \]

    Correct Answer: A

    Solution :

    \[2\sin 2\alpha =\tan \beta +\cot \beta \] \[2.\frac{1}{\cos 2\alpha }=\frac{\sin \beta }{\cos \beta }+\frac{\cos \beta }{\sin \beta }\] \[\frac{2}{\cos 2\alpha }=\frac{{{\sin }^{2}}\beta +{{\cos }^{2}}\beta }{\cos \beta \sin \beta }\] \[\cos 2\alpha =\sin 2\beta \] \[\cos 2\alpha =\cos \left( \frac{\pi }{2}-2\beta  \right)\] \[2\alpha =\frac{\pi }{2}-2\beta \Rightarrow \alpha +\beta =\pi /4\]


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