Strategy for Further Trigonometric Equations (AQA A-Level Mathematics): Flashcards

Multiple angles, compound angles, double-angle identities

$2\sin \theta \cos \theta$

$2\cos^2 \theta - 1$

$\frac{1}{2}[\cos(A-B) - \cos(A+B)]$

For quadratic forms, e.g., $\sin^2 \theta$ and $\sin \theta$

$\theta = \theta_0 + 180^\circ n$

$\theta = \theta_0 + 360^\circ n$

When squaring both sides or using certain identities

$R\cos(\theta \pm \alpha)$

$R = \sqrt{a^2+b^2}$, $\tan\alpha = \frac{b}{a}$