JCECE Engineering JCECE Engineering Solved Paper-2002

  • question_answer
    If\[{{\tan }^{-1}}x+{{\tan }^{-1}}y+{{\tan }^{-1}}z=\pi \], then\[x+y+z\]is equal to:

    A) \[xyz\]                                 

    B) \[0\]

    C)  \[1\]                                    

    D)  \[{{x}^{2}}+{{y}^{2}}+{{z}^{2}}\]

    Correct Answer: A

    Solution :

    Given that                 \[{{\tan }^{-1}}x+{{\tan }^{-1}}y+{{\tan }^{-1}}z=\pi \] \[\Rightarrow \]               \[{{\tan }^{-1}}x+{{\tan }^{-1}}y=\pi -{{\tan }^{-1}}z\] \[\Rightarrow \]               \[{{\tan }^{-1}}\left( \frac{x+y}{1-xy} \right)={{\tan }^{-1}}(-z)\] \[\Rightarrow \]               \[\frac{x+y}{1-xy}=-z\] \[\Rightarrow \]               \[x+y+z=xyz\]


You need to login to perform this action.
You will be redirected in 3 sec spinner