SSC Sample Paper Mock Test-19 SSC CGL Tear-II Paper-1

  • question_answer
    If ABC is a triangle and \[A+B+C=180{}^\circ ,\]then \[\tan A+\tan B+\tan C\]is

    A)  \[\tan A\tan B\tan C\]

    B)         \[\tan \frac{A+B}{2}+\tan \frac{B+C}{2}\]

    C)  \[\frac{\tan A+\tan B}{\tan C}\]

    D)  \[\cot A\cot B\operatorname{cotC}\]

    Correct Answer: A

    Solution :

    As,        \[A+B+C=180{}^\circ \]
    \[\therefore \]      \[A+B=180{}^\circ -C\]
    \[\Rightarrow \]   \[\tan \,\,(A+B)=\tan \,\,(180{}^\circ -C)\]
    \[\Rightarrow \]\[\frac{\tan A+\tan B}{1-\tan A\tan B}=-\tan C\]
    \[\Rightarrow \]\[\tan A+\tan B=-\tan C+\tan A\tan B\tan C\]
    \[\Rightarrow \]\[\tan A+\tan B+\tan C=\tan A+\tan B\tan C\]


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