JEE Main 2021 — Functions Question with Solution
From: JEE Main 2021 (Online) 27th July Evening Shift
Question
Let f : R R be defined as . Then, the value of is equal to :
Choose an option
Show full solutionCorrect option: C
Correct answer
Ccosec2(1) cosec(21) sin(20)
Step-by-step explanation
f(x) = cosx
= 1
So, 1 = cos
= 2
Thus f(x) = cos2x
Now k is natural number
Thus f(k) = 1
)
= 1
So, 1 = cos
= 2
Thus f(x) = cos2x
Now k is natural number
Thus f(k) = 1
)
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This is a previous-year question from JEE Main 2021, covering the Functions chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.