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Question: Answered & Verified by Expert
The number of solutions of the equation tanθ+secθ=2cosθ and cosθ0  lying in the interval 0,2π is
MathematicsTrigonometric EquationsTS EAMCETTS EAMCET 2021 (04 Aug Shift 2)
Options:
  • A 1
  • B 2
  • C 3
  • D 4
Solution:
1629 Upvotes Verified Answer
The correct answer is: 2

Given trigonometric equation is,

tanθ+secθ=2cosθ

sinθcosθ+1cosθ=2cosθ

1+sinθ=2cos2θcosθ0;θπ2,3π2 in 0,2π

1+sinθ=21-sin2θ

2sin2θ+sinθ-1=0

2sin2θ+2sinθ-sinθ-1=0

2sinθ-1sinθ+1=0

Either sinθ=12 or sinθ=-1

θ=π6,5π6,3π2

But θ can not be 3π2

θ=π6,5π6

Hence, number of solutions are 2.

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