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

  • question_answer
    Which of the following functions has period \[2\pi \]?

    A) \[y=\sin \left( 2\pi t+\frac{\pi }{3} \right)+2\sin \left( 3\pi t+\frac{\pi }{4} \right)+3\sin 5\pi t\]

    B) \[y=\sin \frac{\pi }{3}t+\sin \frac{\pi }{4}t\]

    C) \[y\sin t+\cos 2t\]

    D) None of these

    Correct Answer: C

    Solution :

    We have two functions \[f(x)\]and \[g(x)\] have periods \[{{T}_{1}}\] and \[{{T}_{2}}\] respectively, then each of \[f(x)\pm g(x);\] \[f(x).g(x);\]\[f(x)/g(x),\] provided \[g(x)=0\]has period equal to the LCM of \[{{T}_{1}}\] and \[{{T}_{2}}\]. Now, we know that \[sin\text{ }x\]or \[cos\text{ }x\]has period \[2\pi \] Hence period of \[y=\sin t+\cos 2t\]is \[2\pi \].


You need to login to perform this action.
You will be redirected in 3 sec spinner