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Question: Answered & Verified by Expert
cosec2θcos2θ-3cosθ+21, if θ belongs to
MathematicsTrigonometric EquationsJEE Main
Options:
  • A 0,π3
  • B π2,π
  • C π3,π2
  • D 0,π4
Solution:
2912 Upvotes Verified Answer
The correct answer is: π3,π2
cos2θ-3cosθ+21cosec2θ=sin2θ
cos2θ-3cosθ+21-cos2θ
2cos2θ-3cosθ+10
2cosθ-1cosθ-10
cosθ12 or cosθ1
So, θπ3,π2 of the given intervals.

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