JEE Main 2021MathematicsTrigonometric EquationsMediumNumerical

JEE Main 2021 — Trigonometric Equations Question with Solution

JEE Main 2021 (26 Feb Shift 1)

Question

If 3cos2x=3-1cosx+1, then number of solutions of the given equation when x∈0,π2 is ________.

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Show full solutionCorrect answer: 1
Correct answer
1

Step-by-step explanation

3cosx2-3cosx+cosx-1=0

⇒3cosx+1cosx-1=0

⇒cosx=1 or cosx=-13 (reject)

⇒x=0 only

Hence, only one solution.

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About this question

This is a previous-year question from JEE Main 2021, covering the Trigonometric Equations 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.