JCECE Engineering JCECE Engineering Solved Paper-2013

  • question_answer
    Period of the function\[\left| {{\sin }^{3}}\frac{x}{2} \right|+\left| {{\cos }^{5}}\frac{x}{2} \right|\]is

    A) \[2\pi \]                                               

    B) \[10\pi \]

    C) \[8\pi \]                                               

    D) \[5\pi \]

    Correct Answer: D

    Solution :

    \[f(x)=\left| {{\sin }^{3}}\frac{x}{2} \right|+\left| {{\cos }^{5}}\frac{x}{5} \right|\] Period of \[{{\sin }^{3}}x\]is\[2\pi \]. \[\Rightarrow \]               Period of\[{{\sin }^{3}}\frac{x}{2}\]is\[\frac{2\pi }{1/2}=4\pi \]. \[\Rightarrow \]               Period of\[\left| {{\sin }^{3}}\frac{x}{2} \right|\]is\[2\pi \].                 Period of\[{{\cos }^{5}}x\]is\[2\pi \]. \[\Rightarrow \]               Period of\[{{\cos }^{5}}\frac{x}{2}\]is\[\left( \frac{2\pi }{1/5} \right)=10\pi \] \[\Rightarrow \]               Period of\[\left| {{\cos }^{5}}\frac{x}{2} \right|\]is\[5\pi \]. Now, period of\[f(x)=\]LCM of\[\{2\pi ,\,\,10\pi \}=10\pi \]


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