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WBJEE · Maths · Functions

Consider the function \(f(x)=\cos x^{2}\). Then,

  1. A \(f\) is of period \(2 \pi\)
  2. B \(f\) is of period \(\sqrt{2 \pi}\)
  3. C \(f\) is not periodic
  4. D \(f\) is of period \(\pi\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(f\) is not periodic

Step-by-step Solution

Detailed explanation

We have, \[ f(x)=\cos x^{2} \] Let \(T\) be the period of \(f(x)\). Then \[ \begin{aligned} & & f(x+T) &=f(x) \\ \Rightarrow & & \cos (x+T)^{2} &=\cos x^{2} \end{aligned} \] But there is no value of \(T\) for which \[ \cos (x+T)^{2}=\cos x^{2} \] \(\therefore f(x)\) is not…