Question 71Asked in BPSC TRE 1.0 (2023) Mathematics Class 11-12

If sin(π cos θ) = cos(π sin θ), then θ isयदि sin(π cos θ) = cos(π sin θ), तो θ है

यदि sin(π cos θ) = cos(π sin θ), तो θ है
  1. A(1/2) cos⁻¹(1/4)(1/2) cos⁻¹(1/4)
  2. Bcos⁻¹(3/4)cos⁻¹(3/4)
  3. C(1/2) sin⁻¹(3/4)(1/2) sin⁻¹(3/4)
  4. DMore than one of the aboveउपर्युक्त में से एक से अधिक
  5. ENone of the aboveउपर्युक्त में से कोई नहीं
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Correct answer: (C) (1/2) sin⁻¹(3/4)(1/2) sin⁻¹(3/4)

Explanation

cos(π sin θ) = sin(π/2 + π sin θ), so π cos θ = π/2 + π sin θ, i.e. cos θ − sin θ = 1/2. Squaring gives 1 − sin 2θ = 1/4, so sin 2θ = 3/4 and θ = (1/2) sin⁻¹(3/4).cos(π sin θ) = sin(π/2 + π sin θ), इसलिए π cos θ = π/2 + π sin θ, अर्थात् cos θ − sin θ = 1/2। वर्ग करने पर 1 − sin 2θ = 1/4, अतः sin 2θ = 3/4 और θ = (1/2) sin⁻¹(3/4)।

From BPSC TRE 1.0 (2023) Mathematics Class 11-12 — Previous Year Paper

This is question 71 of BPSC TRE 1.0 (2023) Mathematics Class 11-12 — Previous Year Paper. See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.