10th Class Mathematics Introduction to Trigonometry Question Bank Trigonometry

  • question_answer
    If \[sec\theta +tan\theta =x,(x\ne 0)\]then \[\mathbf{sec}\theta \]is equal to

    A) \[\left( x-\frac{1}{x} \right),x\ne 0\]

    B) \[2\left( x-\frac{1}{x} \right),x\ne 0\]

    C) \[\left( x+\frac{1}{x} \right),x\ne 0\]

    D) \[\frac{1}{2}\left( x+\frac{1}{x} \right),x\ne 0\]

    Correct Answer: D

    Solution :

    (d): \[sec\theta +tan\theta =x\]    ?.(i) \[\therefore se{{c}^{2}}\theta -ta{{n}^{2}}\theta =1\] \[\Rightarrow \left( sec\theta +tan\theta  \right)\left( sec\theta -tan\theta  \right)=1\] \[\Rightarrow sec\theta -tan\theta =\frac{1}{x}\]    ?(ii) On adding both the equations \[2sec\theta =x+\frac{1}{x}\] \[\Rightarrow sec\theta =\frac{1}{2}\left( x+\frac{1}{x} \right)\]


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