JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Self Evaluation Test - Trigonometric Function

  • question_answer
    If \[(\sin \theta =3\sin (\theta +2\alpha ),\] then the value of \[\tan (\theta +\alpha )+2\tan \alpha \]is

    A) 3                     

    B) 2  

    C) \[-1\]   

    D) 0

    Correct Answer: D

    Solution :

    \[\sin \theta =3\sin (\theta +2\alpha )\Rightarrow \sin (\theta +\alpha -\alpha )=3\sin \] \[(\theta +\alpha +\alpha )\] \[\Rightarrow \,\,\sin (\theta +\alpha )\cos \alpha -\cos (\theta +\alpha )\sin \alpha \] \[=3\sin (\theta +\alpha )\cos \alpha +3\cos (\theta +\alpha )\sin \alpha \] \[\Rightarrow \,-2\sin (\theta +\alpha )\cos \alpha =4\cos (\theta +\alpha )sin\alpha \] \[\Rightarrow \frac{-\sin (\theta +\alpha )}{\cos (\theta +\alpha )}=\frac{2\sin \alpha }{\cos \alpha }\Rightarrow \tan (\theta +\alpha )+2\tan \alpha =0\]


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