JEE Main 2021MathematicsTrigonometric EquationsMediumMCQ

JEE Main 2021 — Trigonometric Equations Question with Solution

JEE Main 2021 (18 Mar Shift 1)

Question

The solutions of the equation 1+sin2xsin2xsin2xcos2x1+cos2xcos2x4sin2x4sin2x1+4sin2x=0,0<x<π, are

Choose an option

Show full solutionCorrect option: D
Correct answer
D7π12,11π12

Step-by-step explanation

1+sin2xsin2xsin2xcos2x1+cos2xcos2x4sin2x4sin2x1+4sin2x=0

use R1→R1+R2+R3

⇒2+4sin2x111cos2x1+cos2xcos2x4sin2x4sin2x1+4sin2x=0

use C1→C1-C3  & C2→C2-C3 

⇒2+4sin2x00101cos2x-1-11+4sin2x=0

⇒2+4sin2x=0

⇒sin2x=-12

⇒2x=π+π6,2π-π6

x=π2+π12,π-π12

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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.