Q62 / 150 · MHT CET 2019 (Shift 2) · Mathematics

If lines represented by 1+sin2θx2+2hxy+2isinθy2=0,θ∈0,2π are perpendicular to each other then θ = ….

  • A
    π2
  • B
    π
  • Correct answer
    C
    3π2
  • D
    π6

Solution

Key Idea Given, ax2+2hxy+by2=0 represents perpendicular pair of straight lines then a + b =0
We have, pair of lines represented by
1+sin2θx2+2hxy+2xinθy2=0,θ∈0,2π
∴1+sin2θ+2sinθ=0
⇒1+sinθ2=0
⇒1+sinθ=0
⇒sinθ=-1=-sinπ2=sin⁡2π-π2
⇒sinθ=sin3π2⇒θ=3π2

Hence, the correct answer is option: 'C'.

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