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If F(X) = Cos [π2]X + Cos [−π2] X, Where [X] Denotes the Greatest Integer Less than Or Equal to X, Then Write the Value of F(π). - Mathematics

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Question

If f(x) = cos [π2]x + cos [−π2x, where [x] denotes the greatest integer less than or equal to x, then write the value of f(π).

Solution

f(x) = cos [π2]x + cos [−π2x

\[\text{ Thus } , f(\pi) = \cos\left[ \pi^2 \right] \pi + \cos \left[ - \pi^2 \right] \pi\]
\[ \Rightarrow f(\pi) = cos \left[ 9 . 8 \right]\pi + cos\left[ - 9 . 8 \right]\pi\]
\[ \Rightarrow f(\pi) = cos  10\pi + cos 9\pi\]
\[ \Rightarrow f(\pi) = 1 + ( - 1) = 0\]

 

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Chapter 3: Functions - Exercise 3.5 [Page 41]

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RD Sharma Mathematics [English] Class 11
Chapter 3 Functions
Exercise 3.5 | Q 4 | Page 41

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