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

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

Three forms: $\cos^2(\theta) - \sin^2(\theta)$, $2\cos^2(\theta) - 1$, $1 - 2\sin^2(\theta)$

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

$\sin(2\theta) = 24/25$

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

$\theta = 22.5°$ or $112.5°$

Simplifying trigonometric expressions.

They simplify integrals and derivatives.

$\cos(3\theta) = 4\cos^3(\theta) - 3\cos(\theta)$

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