JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Self Evaluation Test - Trigonometric Function

  • question_answer
    The value of \[{{\tan }^{2}}\theta {{\sec }^{2}}\theta ({{\cot }^{2}}\theta -{{\cos }^{2}}\theta )\] is

    A) \[0\]    

    B) \[1\]    

    C) \[-1\]    

    D) \[\frac{1}{2}\]

    Correct Answer: B

    Solution :

    \[{{\tan }^{2}}\theta \,\,se{{c}^{2}}\theta ({{\cot }^{2}}\theta -{{\cos }^{2}}\theta )\] \[={{\sec }^{2}}\theta ({{\tan }^{2}}\theta {{\cot }^{2}}\theta -{{\tan }^{2}}\theta {{\cos }^{2}}\theta )\] \[={{\sec }^{2}}\theta \left( 1-\frac{{{\sin }^{2}}\theta }{{{\cos }^{2}}\theta }{{\cos }^{2}}\theta  \right)={{\sec }^{2}}\theta (1-{{\sin }^{2}}\theta )\] \[={{\sec }^{2}}\theta .\,{{\cos }^{2}}\theta =1\]


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