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Saxbophone · Answer 1 · 2020-11-23T23:00:29+0000

by using identity sin²θ=1 - cos²θ

3sin²θ = 4cosθ - 1

3(1 - cos²θ) = 4cosθ - 1

3 - 3cos²θ = 4cosθ - 1

3cos²θ + 4cosθ - 4 = 0

(3cosθ - 2)(cosθ + 2) = 0

cosθ = ⅔

θ = 48.19° or θ = 311.81°

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