JEE Main & Advanced Mathematics Trigonometric Equations Question Bank Solution of trigonometrical equations

  • question_answer
    The number of solutions of the given equation \[\tan \theta +\sec \theta =\sqrt{3},\] where \[0<\theta <2\pi \]is

    A) 0

    B) 1

    C) 2

    D) 3

    Correct Answer: C

    Solution :

    \[\sec \theta +\tan \theta =\sqrt{3}\] ?.(i) Also we have \[{{\sec }^{2}}\theta -{{\tan }^{2}}\theta =1\] ?..(ii) \[\Rightarrow \] \[\sec \theta -\tan \theta =\frac{1}{\sqrt{3}}\] ?..(iii) Now (i) and (iii) gives, \[\tan \theta =\frac{1}{2}\left( \sqrt{3}-\frac{1}{\sqrt{3}} \right)=\frac{1}{\sqrt{3}}=\tan \left( \frac{\pi }{6} \right)\] \[\Rightarrow \] \[\theta =n\pi +\frac{\pi }{6}\]. \[\therefore \] Solutions for \[0\le \theta \le 2\pi \] are \[\frac{\pi }{6}\] and \[\frac{7\pi }{6}\]. Hence there are two solutions.


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