J & K CET Engineering J and K - CET Engineering Solved Paper-2013

  • question_answer
    If  \[\sin B=3\sin (2A+B),\] then \[2\tan A+\tan (A+B)\] is equal to

    A)  \[0\]                   

    B)  \[-2\]

    C)  \[1\]                     

    D)  \[1\]

    Correct Answer: A

    Solution :

    Given that,  \[\sin B=3\sin (2A+B)\] \[\Rightarrow \] \[\frac{\sin \,\,B}{\sin \,(2A+B)}=\frac{3}{1}\] \[\Rightarrow \] \[\frac{\sin B+\sin (2A+B)}{\sin B-\sin (2A+B)}=\frac{3+1}{3-1}\] (use componendo-dividendo formula) \[\Rightarrow \] \[-\frac{2\sin \,(A+B).cos(A)}{2\cos \,(A+B).\sin (A)}=\frac{4}{2}\] \[\Rightarrow \] \[\tan (A+B).\cot \,A=-2\] \[\Rightarrow \] \[\tan \,(A+B)=-2\tan A\] \[\Rightarrow \] \[2\tan A+\tan (A+B)=0\]


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