JEE Main 2016MathematicsTrigonometric EquationsMediumMCQ

JEE Main 2016 — Trigonometric Equations Question with Solution

JEE Main 2016 (03 Apr)

Question

If 0 ≤x<2π, then the number of real values of x, which satisfy the equation cosx+cos2x+cos3x+cos4x=0, is 

Choose an option

Show full solutionCorrect option: A
Correct answer
A7

Step-by-step explanation

2cos2xcosx+2cos3xcosx=0

⇒ 2cosxcos2x+cos3x=0

2cosx2cos5x2cosx2=0

x=π2,3π2, π,π5,3π5,7π5,9π5

7 Solutions.

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About this question

This is a previous-year question from JEE Main 2016, 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.