Practicing Success
If $3 \sec \theta+4 \cos \theta-4 \sqrt{3}=0$ where $\theta$ is an acute angle then the value of $\theta$ is: |
20° 30° 60° 45° |
30° |
3 secθ + 4 cosθ - 4√3 = 0 3 × \(\frac{1}{cosθ}\) + 4 cosθ - 4√3 = 0 4 cos²θ - 4√3cosθ + 3= 0 4 cos²θ - 2√3cosθ - 2√3cosθ + 3= 0 2cosθ (2cosθ - √3) - √3 (2cosθ - √3) = 0 (2cosθ - √3)² = 0 cosθ = \(\frac{√3}{2}\) { cos30º = \(\frac{√3}{2}\) } So, θ = 30º
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