JEE Main & Advanced Mathematics Functions Question Bank Self Evaluation Test - Relation and Functions-II

  • question_answer
    The graph of the function \[\cos x\,\cos \,(x+2)-co{{s}^{2}}(x+1)\] is

    A) A straight line passing through \[(0,-si{{n}^{2}}1)\] with slope 2

    B) A straight line passing through (0, 0)

    C) A parabola with vertex \[(1,-si{{n}^{2}}1)\]

    D) A straight line passing through the point \[\left( \frac{\pi }{2},-{{\sin }^{2}}1 \right)\]and parallel to the x-axis.

    Correct Answer: D

    Solution :

    [d] \[y=\frac{1}{2}[cos(2x+2)+cos2-\{1+cos(2x+2)\}]\] Or \[y=-\frac{1}{2}\,(1-cos2)=-si{{n}^{2}}1\] i.e. constant \[\therefore \]Graph is a line parallel to x-axis. Also when \[x=\frac{\pi }{2},y=-{{\cos }^{2}}\left( \frac{\pi }{2}+1 \right)=-{{\sin }^{2}}1\] and hence it passes through the point \[\left( \frac{\pi }{2},-{{\sin }^{2}}1 \right)\]


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