01 Trignometric
Rule | |||
---|---|---|---|
Product | |||
Sum | |||
\(\cos C - \cos D\) | \(-2 \sin \left( \frac{C+D}{2} \right) \sin \left( \frac{C-D}{2} \right)\) | ||
\(\tan(x+y)\) | \(\frac{\tan x + \tan y}{1 - \tan x \tan y}\) | ||
\(\tan(x-y)\) | \(\frac{\tan x - \tan y}{1 + \tan x \tan y}\) | ||
Double | \(\sin 2x\) | \(2 \sin x \cos x\) | \(\frac{2 \tan x}{1 + \tan^2 x}\) |
\(\cos 2x\) | \(\cos^2 x - \sin^2 x\) \(2\cos^2 x - 1\) \(1 - 2 \sin^2 x\) | \(\frac{1-\tan^2 x}{1 + \tan^2 x}\) | |
\(\tan 2x\) | \(\frac{2 \tan x}{1 - \tan^2 x}\) | ||
\(\cot 2x\) | \(\frac{\cot^2 x - 1}{2 \cot x}\) | ||
Triple | \(\sin 3x\) | \(3 \sin x - 4\sin^3 x\) | |
\(\cos 3x\) | \(4\cos^3 x - 3\cos x\) | ||
\(\tan 3x\) | \(\frac{3\tan x - \tan^3 x}{1 - 3 \tan^2 x}\) | ||
\(\cot 3x\) | \(\frac{3 \cot x - \cot^3 x}{1 - 3 \cot^2 x}\) | ||
Half | \(\tan \frac{x}{2}\) | \(\text{cosec }x - \cot x\) | \(\sqrt{\frac{1-\cos x}{1+\cos x}}\) |
\(\cot \frac{x}{2}\) | \(\text{cosec }x + \cot x\) | \(\sqrt{\frac{1+\cos x}{1-\cos x}}\) |