JEE Main & Advanced Mathematics Binomial Theorem and Mathematical Induction Question Bank Mock Test - Principle of Mathematical Induction

  • question_answer
    The product of \[\cos \theta \cos 2\theta \cos 3\theta ...\cos ({{2}^{n-1}}\theta )\]is

    A) \[\frac{\sin ({{2}^{n}}\theta )}{{{2}^{n}}\sin \theta }\]           

    B) \[\frac{cos({{2}^{n}}\theta )}{{{2}^{n}}\cos \theta }\]

    C) \[\frac{cosn\theta }{{{2}^{n}}\cos \theta }\]     

    D) \[\frac{sin({{2}^{n}}\theta )}{\sin \theta }\]

    Correct Answer: A

    Solution :

    [a] By setting n=1, given expression becomes \[\cos \theta \]. By setting n=1, option (1) becomes \[\frac{\sin 2\theta }{2\sin \theta }=\frac{2\sin \theta \cos \theta }{2\sin \theta }=\cos \theta \].


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