Double Angle Formulae (AQA A-Level Mathematics): Flashcards

$2\sin(\theta)\cos(\theta)$

$\cos^2(\theta) - \sin^2(\theta)$

$2\cos^2(\theta) - 1$

$1 - 2\sin^2(\theta)$

Three

$\frac{2\tan(\theta)}{1 - \tan^2(\theta)}$

Trig functions of $2\theta$ in terms of $\theta$

Simplify integrals/derivatives with trig functions

Wave mechanics, signal processing, oscillations

To avoid losing solutions