Practicing Success
For θ : 0° < θ < 90° $3 sec θ + 4 cos θ = 4 \sqrt{3}$, find the value of ( 1 - sin θ + cos θ) |
$\frac{1+2\sqrt{3}}{2}$ $\frac{1+\sqrt{3}}{2}$ $\frac{1-\sqrt{3}}{2}$ $\frac{1-2\sqrt{3}}{2}$ |
$\frac{1+\sqrt{3}}{2}$ |
3secθ + 4 cosθ = 4√3 3( \(\frac{1}{cosθ}\)) + 4 cosθ = 4√3 3 + 4 cos²θ = 4√3 cosθ 4 cos²θ - 4√3 cosθ + 3 = 0 4 cos²θ - 2√3 cosθ - 2√3 cosθ + 3 = 0 2 cosθ( 2cosθ - √3 ) - √3( 2cosθ - √3 ) = 0 ( 2cosθ - √3 ). ( 2cosθ - √3 ) = 0 2cosθ - √3 = 0 cosθ = \(\frac{√3}{2}\) { cos 30º = \(\frac{√3}{2}\) } Now, 1 - sinθ + cosθ = 1 - sin30º + cos30º = 1 - \(\frac{1}{2}\) + \(\frac{√3}{2}\) = \(\frac{1 + √3}{2}\) |