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If $ 7sin^2 θ + 3cos^2 θ = 4, 0° < θ < 90 °$, then the value of θ will be : |
60° 45° 75° 30° |
30° |
$ 7sin^2 θ + 3cos^2 θ = 4, 0° < θ < 90 °$ 7sin²θ + 3 ( 1 - sin² θ ) = 4 { sin²θ = 1 - cos² θ } 4sin²θ + 3 = 4 sin²θ = \(\frac{1 }{4}\) sinθ = \(\frac{1 }{2}\) And we know sinθ is \(\frac{1 }{2}\) only if θ = 30° Ans:- 30° |
