Practicing Success
2 cos θ + sec - $2\sqrt{2}$ = 0, where is an acute angle. Find the value of θ. |
30° 15° 60° 45° |
45° |
2 cosθ + secθ - 2√2 = 0 2 cosθ + \(\frac{1}{cosθ}\) - 2√2 = 0 2 cos²θ - 2√2 cosθ + 1 = 0 2 cos²θ - √2cosθ - √2cosθ + 1 = 0 √2cosθ ( √2 cosθ - 1 ) -1 ( √2 cosθ - 1 ) = 0 ( √2 cosθ - 1 ) .( √2 cosθ - 1 ) = 0 ( √2 cosθ - 1 ) = 0 cosθ = \(\frac{1}{√2}\) { cos45º = \(\frac{1}{√2}\)} So, θ = 45º
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