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

Trig functions in quadratic form ($\sin^2\theta$, $\cos^2\theta$, $\tan^2\theta$)

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

Factoring, quadratic formula, substitution

Let $u =$ trig function and substitute

Back-substitute $u$ with original trig function

Between $-1$ and $1$

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

$\sin^2(\theta)$

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

$90^\circ$