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If x + y = 3 - cos ⁡ 4 θ and x - y = 4 sin ⁡ 2 θ , then the value of x + y is equal to

Options

  1. A2
  2. B4
  3. C6
  4. D8

Correct answer

A. 2

Step-by-step solution

Adding both the given equations, we get, 2 x = 3 + 4 sin ⁡ 2 θ - cos ⁡ 4 θ = 3 + 4 sin ⁡ 2 θ - 1 - 2 sin 2 ⁡ 2 θ = 2 sin 2 ⁡ 2 θ + 4 sin ⁡ 2 θ + 2 ⇒ x = sin 2 ⁡ 2 θ + 2 sin ⁡ 2 θ + 1 ⇒ x = sin ⁡ 2 θ + 1 2 Similarly, 2 y = 3 - cos ⁡ 4 θ - 4 sin ⁡ 2 θ 2 y = 3 - 4 sin ⁡ 2 θ - 1 - 2 sin 2 ⁡ 2 θ = 2 sin 2 ⁡ 2 θ - 4 sin ⁡ 2 θ + 2 ⇒ y = sin 2

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