Quadratic Trigonometric Equations (AQA A-Level Mathematics): Quizzes

$a \cdot (\text{trig})^2 + b \cdot (\text{trig}) + c = 0$

Between $-1$ and $1$

Let $u = \sin \theta$ and substitute

$90^\circ, 210^\circ, 330^\circ$

$\cos \theta$ must be between $-1$ and $1$

$60^\circ, 120^\circ, 240^\circ, 300^\circ$

$0^\circ$ to $360^\circ$ or $0$ to $2\pi$ radians

$u = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$

$60^\circ$ or $240^\circ$

$0.2808$ only