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Question: Answered & Verified by Expert
If cosecθ+cotθ=13, then θ lies in the
MathematicsTrigonometric Ratios & IdentitiesAP EAMCETAP EAMCET 2020 (23 Sep Shift 1)
Options:
  • A 1st quadrant 
  • B 2nd quadrant
  • C 3rd quadrant
  • D 4th
Solution:
1218 Upvotes Verified Answer
The correct answer is: 2nd quadrant

cosecθ+cotθ=13

1+cosθsinθ=13

3+3cosθ=sinθ

Squaring

9cos2θ+18cosθ+9=1-cos2θ

10cos2θ+18cosθ+8=0

5cos2θ+9cosθ+4=0

5cos2θ+5cosθ+4cosθ+4=0

5cosθ(cosθ+1)+4(cosθ+1)=0

cosθ=-1, -45

cosθ=-45θ lies in 2nd or 4th quadrant

But cosecθ+cotθ is positive

So θ lies in 2nd quadrant

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